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View Full Version : Time to get rid of timing chain noise. Any tips?



SOHC240
02-06-2002, 09:55 PM
What are the common problems on the SOHC regarding the chain rattle?

Tensioners, guides, chain, or sprockets? Can I get away with just changing parts of it or should I change everything?

What are all the parts I need to do the job?

Also how do I know when #1 cylinder is at TDC? And how do I make sure the sprockets are at the right spot when I put the chain back on?

Any other tips for the do it yourselfers? (Me)

Thanks alot!
Marshall

**DONOTDELETE**
02-07-2002, 12:17 AM
This is straight from the 240sx.org FAQ. Maybe this will help.

Q: I have a 1989 Nissan 240SX SE hatchback with 120,000 miles on it and I was curious what the concensus is on timing belt replacement?

A: First off, it's a chain, not a belt, so it's not a wear item.

Q: I have had some mechanics tell me that I don't need to worry about it as long as I haven't been "abusive" to the engine. And I have had others tell me that you should just have it done at 60 or 80k. So I have three questions:
Q: 1) is the '89 240SX SE an 'interference' engine (timing belt goes, valves and pistons crash catostrophically) or not?

A: Yes. If your chain breaks (never happens) or starts jumping teeth on the gears (more on this later) it can munch the valves.

Q: 2) what is the recommended replacement interval?

A: Doesn't apply.

Q: 3) what is the going rate for such a repair?

A: It typically costs $500-$700 to have the chain, sprockets, tensioner, chain guides, and front-cover seals replaced.

Q: PS- also do I have a chain or belt? and does it make that significant a difference in change intervals, cost etc?

A: There's a technical service bulletin out for most of the 240SXs (can't remember the years, but yours is *definitely* one of them) which recommends replacement of the chain guides and chain tensioner.

Here's what I told Tony, the other guy who asked about this today:

> Tony Iannarelli wrote:
> >
> > What are the symptoms of the Timing Chain going bad?
>
> Well, it's not so much that the chain goes bad, but the tensioner
> gets weak and the guides break into little bits. This is a Nissan
> technical service bulletin, which means it's a known problem and
> there are upgraded parts available to correct it, but it's not a
> recall, so you have to pay to have it done.
>
> The usual symptoms are that the engine rattles like hell when you
> first start it (chain flapping around) and lacks power (slack chain
> causing camshaft timing to drift around unpredictably).
>
> It's a 10-12 hour job for your typical do-it-yourselfer, but it's one
> of the more annoying jobs I've done on my car. If you can afford it,
> I would advise you to have a shop do it -- and the independent shops
> do just as good a job as the dealerships, for less money.
>
> You can even order the parts at discount from Brown & Brown Nissan
> of Arizona -- http://www.brownandbrown.com, or via their 800-number
> in the back of Car and Driver or other car mags.

Hope this helps.

-Trevor

Q> Does a 1993 240sx se have a timing chain or is it a belt???

A> It's all chains. All KA24E/DE have timing chains along w/ SR20DE. Belts are found on the VQ/VG engines.

tyyap

$5 solution to the DOHC chain rattle problem

I found a $5 solution to the chain rattle problem!!!! Well, at least *our* chain rattle problem.

Background: We got a DOHC engine with 53k miles on it from a junkyard, where it had been sitting on the rack for about 1 year or so. It had the nasty chain rattle problem that was always present not matter if the engine was hot or cold.

The problem that I found was the tensioner was *frozen* and was not fully extending and keeping tension on the chain. The burnt on oil/sludge gunk was keeping the tensioner from moving freely in the bore. Here's a quick rundown on how to fix this problem. Of course, if your chain is stretched and the guides are worn, this won't help you.

Tools needed: 10 and 12 mm wrenches, long screwdriver, timing light (very helpfull, but not totally necessary), tube of RTV, WD-40. A big socket to fit the front crank bolt is also helpfull but not required.

1. Put the engine at TDC (with #1 cylinder firing) because you'll be pulling the distributor out and you don't want to play guessing games on how to put it back in. Pull the cap from the distributor and make a note of where the rotor is pointing. Also make a scribe mark on where the distributor is adjusted so you can get the timing real close when you restart the car. If you don't have a socket to fit the front crank bolt to turn the engine, put the car in 4th gear (sorry slushers), and roll it back and forth until the engine is at TDC.

2. Remove the valve cover. You may need to remove the fan, depending on the amount of room you need. Remove the 3 small bolts (10mm head) holding the upper timing cover the lower cover. Remove the other 5 or 6 bolts (12mm). Carefully remove the top cover. If it doesn't just pop off, make sure all of the bolts are removed, otherwise you'll crack something!!!!

3. With the top timing cover removed, you can now access the top tensioner and the bottom tensioner. If found that both were a bit sticky, with the bottom one being the worst. It was jammed inside the bore and wasn't moving at all. As a result, the chain was just flapping in the wind.

4. Use a flat bladed screwdriver or other instrument of choice, to pop the tensioner out against the chain. Then, push it back into the tensioner housing until it bottoms. When you let go of the tensioner, it should pop back out and put full tension on the chain. If it doesn't pop it back out. Push in, pop out, push in, pop out, etc.... Do this until the tensioner is moving freely. I used a bit of penetrating oil (rusted bolt remover), to help disolve the gunk and get things moving freely. Check both tensioners.

5. Clean the cover, removing all of the RTV sealant. Clean the other mating surface and put the cover back on with new RTV. Replace the valve cover. Put the distributor back in, making sure it lined up as before. Fire it up,check the distributor timing, and enjoy the silence.

Notes:

Take a look at the guides while you're in there. Look for grooving and wear.

The little swinging latch on the tensioner is for holding the tensioner when you change the chain. Just ignore it and let it hang down.

When you're putting the bolts back into the front cover, go easy on the tightening. They are threading into aluminum and they are pretty easy to strip.

If the car won't start or runs like crap, put the engine back at TDC (with #1 cylinder firing) and double check that you got the distributor back in right.

When you're poking around at the tensioner and cleaning off the old RTV, make sure not to drop goobers (bits of RTV and gasket material) down the front cover.

-----------------------------------------------------------
| Dave Balingit - Data Tech Racing
| 240SX NASA Pacific Coast Touring Car
| Nissan/Infiniti Speedvision Cup Car
| david@gwcom.com : datatech@garlic.com
| http://www.garlic.com/~datatech

Timing chain rattle

I was told by some that a rattling noise from the engine could mean the timing chain needed to be replaced. I found that might be true sometimes but I think the real thing that makes the timing chain rattle is simply a metal plate that runs across the two cams. When talking to a mechanic he said the dealerships solution for fixing the rattling sounds were to simply remove the metal plate. To do this all you need to do is take off the valve cover and remove the two bolts holding it in. Hope this makes someone happy.

Simon
Email: ss82480@aol.com

Timing Chain Part Numbers for SOHC:

To you who are interested, I called up NissanAutoParts.com and put in a quote for the necessary stuff to change a timing chain. Here it is:
NissanAutoParts.com QUOTE!!!
-------------------------------------------------------
(1) Qnty: 1 Part#: 13028-8B000 ---->Total Price: 30.60
Description: chain
(2) Qnty: 1 Part#: 13070-40f06 ---->Total Price: 17.26
Description: tensioner
(3) Qnty: 1 Part#: 13085-40F10 ---->Total Price: 7.13
Description: slackl side guide
(4) Qnty: 1 Part#: 13075-40F10 ---->Total Price: 1.46ea
Description: bolt for s guide
(5) Qnty: 1 Part#: 13091-40F15 ---->Total Price: 7.26
Description: tension side guide
(6) Qnty: 1 Part#: 13510-53F10 ---->Total Price: 4.82
Description: frt crank seal
(7) Qnty: 1 Part#: 15066-5E500 ---->Total Price: 3.34
Description: frt cover seal
+ Shipping & Handling:
-----------------------------------
=======>TOTAL: $71.87 USD
-----------------------------------
I don't think that's too bad myself!
Brent Lykins
dblykins@email.msn.com

Timing Chain Rubbing Against Valve Cover!

Solution:

I just recently brought my '92 SE into the local dealership for some warranty work - Timing Chain making a strange rubbing sound but not quite a rattle, as well as replacing the tranmission seals for major leaks. I was surprised that the chain has no exact replacement "time frame". The people at the Nissan dealership basically said that it is not considered a wear item and that the chain is only replaced if it actually is damaged itself! They then explained that the cause of the sound was the main guide on the top of the timing chain - A part that has been deleted from the Nissan inventory! It has been recommended that this part is nolonger necessary and should simply be removed. With the guide gone the chain no longer makes any "strange" noises. Also, my terrible warranty people initially denied to pay for the guide's removal but when I demanded that Nissan provide them with the documentation indicating that this was a part no longer needed but not a recall they immediately ! reviewed my case and are going to reimburse me for that "repair". Once I get a scanner I post up that Documentation. This only applies to the DOHC 240's.

Steve
Email: stevend23@hotmail.com


Jared

Mav1178
02-07-2002, 03:17 AM
Be sure to ignore the info on the DOHC engine.

-alex

pchio
02-07-2002, 04:38 AM
My DOHC engine is also making that timing chain rattling noise. Does anyone has any info or step by step guide to fix this problem without bringing it to auto-shop?

Thanks,
Pat

pchio
02-07-2002, 05:02 AM
Ok I just checked the old posts, and here are some information from Alex:

-1) Nissan issued a TSB for 1989-1990 S13 KA24E engines. They found that the lower timing chain guide (big long plastic one) was prone to break if the timing chain had slack in it. If service was needed, Nissan replaces that with a guide that has a metal plate backing on it.
-2) BEFORE YOU ASSUME ANYTHING, take off the top -guide. If that doesn't fix your problem (and the sounds are coming more from the front cover than the valves) then get an oil pressure gauge and check your oil pressure. If you have low oil pressure, the reason for your rattle is the tensioner not putting enough tension on the timing chain and the chain has slack in it and are hitting the plastic guides.
-3) If you have rattle (especially at startup), try running 5-30 oil for the next oil change and use an OEM Nissan oil filter. Often times, the rattle @ startup is caused by the tensioner having a lack of oil and/or the system in the engine is dry. Using aftermarket filter that are not as good as an OEM filter may contribute to that problem.

-That's how my engine blew after 3+ years of the timing chain rattle.
I had a rattle at idle (and especially when the engine was cold), and I neglected to get it fixed. Then last summer my KA engine died on me while driving home from school.
Get the timing chain tensioners, chain guides, chains, and oil pump replaced at the same time. It may seem like a lot of parts and time, but it will save you from a blown engine later down the road.

P.S. Again, Thanks Alex!

[ 02-07-2002, 05:03 AM: Message edited by: pchio_s14 ]

Mav1178
02-07-2002, 02:32 PM
Originally posted by pchio_s14:
My DOHC engine is also making that timing chain rattling noise. Does anyone has any info or step by step guide to fix this problem without bringing it to auto-shop?
<font size="2" face="Verdana, Arial[/img]Patrick,

On the DOHC engine, there are two chain guides for the upper timing chain.

The upper timing chain tensioner is the only surface the chain touches (in addition to the idler gear and the cam gears).

These two chain guides are designed as a failsafe device, in case of completely loss of oil pressure. Without out them, the timing chain would simply slack out and start skipping the teeth on the cam gears (if you ever suddenly lose oil pressure). It could potentially cause you to bend valves, as the KA is an interference design engine.

A 240SX list member posted this on the tech list last year:

-----Original Message-----
From: 240-tech-bounce@amarok.org [mailto:240-tech-bounce@amarok.org]On
Behalf Of Scott Thomas
Sent: Thursday, July 19, 2001 1:45 PM
To: 240-tech@amarok.org
Subject: [240-tech] DOHC timing chain rattle - important notice

Not sure if this is common knowledge, but I just found out today - I know it is well known that the upper timing chain guide on TOP of the timing chain has been removed from service because it is unnecessary and tends to break (mine did) - but also the LOWEr chain guide on the UPPER chain has also been abolished by Nissan (You must remove the upper cover to take this off, see the section under "FAQ - Timing chain Q&A, $5 solution for the procedure). IMO this is even more important because whereas when the upper one breaks it tends to just sit on top of the chain and rattle, if the lower one broke it would probably fall down inside the lower cover and tear things up pretty badly - bye-bye engine.

IMO, Nissan should recall these - when I pulled my broken upper guide out after I first bought the car, it was chewed halfway through and if it had been cut in two, the smaller pieces (as well as metal shavings) could have wandered around the rockers or down the timing cover and done some serious damage. Not to mention I doubt it is particularly good for the chain (though mine didn't show any visible wear).

Scott Thomas Stock 92 Fastback 137K miles
*****************************

I think this is one of the most important pieces of info regarding the DOHC timing chain. As you may or may not know, the SOHC timing chain is one chain that directly connects the crank to the cams, and the SOHC engine has an oil pump that is both easy to replace, and can fail easy. The DOHC engine, however, has a two stage timing chain assembly. It is difficult to replace the oil pump (as it is built into the lower chain cover), and often when you are told to remove the upper top chain guide (above the cams), the timing chain rattle is still there.

By removing the lower guide on the upper chain, it actually helps protect the engine. Why?

The info you posted regarding my engine failure (from two summers ago) is somewhat accurate. When I took apart that engine, I found out what was the problem. I had taken off the top guideon the upper timing chain , like everyone else told me to, but I still had the timing chain rattle. When I pulled the front cover of my blown engine, I saw that the lower metal guide on the upper chain completely snapped off (due to too much wear from the upper chain rubbing against it), and it got wedged where the idler gear was and chopped the upper timing chain in half.

I have since taken Scott Thomas' advice and removed both upper timing chain guides when I swapped my stock KA head for a DPR-ported head. I have run 2 track events and logged over 8k miles since then, with no problems or any sort of timing chain noise.

This is not to say that removing the guides can solve what is causing the chain to rattle against the guides in the first place. IMO you should make sure that the tensioner isn't stuck, and you should also have your oil pressure checked. The rattle is basically caused by two things:

1) Low oil pressure going to tensioner (it is driven by oil pressure, whether it be from a bad oil pump or blocked oil passages.

2) Stuck/defective tensioner.

I hope you can visualize what I am describing to you. Just wanted to tell you that by simply removing the guides or trying to dislodge the tensioner may solve the problem temporarily, but it won't be a permanent fix.

-alex

Mav1178
02-07-2002, 02:35 PM
Originally posted by pchio_s14:
Ok I just checked the old posts, and here are some information from Alex:

-2) BEFORE YOU ASSUME ANYTHING, take off the top -guide. If that doesn't fix your problem (and the sounds are coming more from the front cover than the valves) then get an oil pressure gauge and check your oil pressure. If you have low oil pressure, the reason for your rattle is the tensioner not putting enough tension on the timing chain and the chain has slack in it and are hitting the plastic guides.
<font size="2" face="Verdana, Arial[/img]I have to say that what I posted before was slightly inaccurate.

The rattle you hear is not from the timing chain hitting the plastic guide, it is from the upper timing chain hitting the lower chain guide on the upper chain.

Basically caused by the two reasons I previously posted.

-alex

**DONOTDELETE**
02-07-2002, 05:56 PM
You guys NEEEEEEEEEEEEEED to separate the two motors in this discussion. The SOHC and DOHC greatly differ and suffer from 2 different problems.

Chances are, if you have a DOHC and you are hearing chain rattle.. then you need to follow the common steps to either replacing the worn chain OR fixing/removing the guides.

The SOHC motor however, has a tendancy to rattle on startup.. especially as it gets older. My `90 has around 150k and after the car sits for a while, the car WILL rattle on startup for a good 2-3 seconds.. depending on the idle speed. If the idle is lower, the rattle is less noticeable.

The important thing to monitor with an SOHC motor is your oil pressure and to make sure your oil is at a normal level, and that the pump is operational. I run Castrol GTX 5W-30 or 10W-40 w/ NISSAN filter and the car still has a tendency to rattle.

As it stands, there are two theories I have to check out.

1) I hear the tensioner MAY be adjustable. I am going to look into slotting it or setting it so that I can move it a little close to the chain. I may even consider increasing the tension on the spring. I need to do something to increase tension.

2) I heard the rattle on older cars could be worn bearings. Since the bearings are worn, establishing pressure MAY take a lill longer than it used to. I have no way of knowing this until I tear the motor apart.. but its a thought. I will see if running thicker oil helps.

Anyway, just some thoughts that me and some friends had. REMEMBER, if you hear a chainsaw sound or rattle when the car is warm, your chain NEEDS replacement - PERIOD. I had that happen to me at 100k, so I changed the chain and NO more problems.

I've already changed lifters and oil pump, so I know those are fine. Its just a matter of time..

- Mike

**DONOTDELETE**
02-07-2002, 08:49 PM
i just glanced through this thread but it looks like no one actually mentioned the writeup in the installs section of www.240sx.org (http://www.240sx.org) on doing the SOHC timing chain job. it gives all the necessary details and is an easy to follow guide (unless you're me, in which case you read through it and do the whole job with a big hammer haphazardly checking off the steps in random order... http://www.freshalloy.com/ )

if you have the timing chain rattle at startup, get around to fixing it. if you have it for 5 minutes of first driving the car, GET IT FIXED NOW! when you get the startup rattle it's probably because the tensioner's lazy and doesnt pressurize without oil in it, doesn't sound too bad BUT, because it's lazy it gives the chain extra slack which causes it to do a faster job of chewing through the guides. and i mean METAL guides. the plastic ones will eventually shatter, the metal ones get grooves eaten into them. i'm sure it's no picnic for the chain itself either. in all the whole system gets slack in it.

once it gets enough slack, the straight guide goes. especially if it's the old plastic type. once that happens the chain will be slack for the first 10 or so minutes of driving, you'll hear it. it will jump around and hit the front cover. it doesnt CHEW through the front cover, it CRACKS it and i'm guessing the sucker will evenutally shatter rather than be sawed through. and you can't quite see it if you just take the valve cover off (i mean the front cover damage, you should be able to make out a shattered guide).

so if you're thinking of getting rid of the startup rattle, go ahead and use the directions in the installs on www.240sx.org, (http://www.240sx.org,) have an FSM handy if you can, a spare ride comes in great handy, give yourself a good number of days to do the job and replace everything while you're in there since it's a ******* having to do it again...

pchio
02-07-2002, 09:28 PM
Ok, first of all, these questions is for the DOHC timing chain problem.

I decided to get it fix ASAP, coz the nosie is getting louder and louder http://www.freshalloy.com/ . I just checked courtnissan parts website and I found the timing chain replacment kit. Here is the link:
Courtesy Nissan Parts Timing Chain replacment kit (http://www.courtesyparts.com/S14-TBKIT.html)

The kit is about $400 total, but I think I don't need the whole kit to fix the rattling problem. Can someone tell me which parts I should get?

Also, do I need to replace the Lower timing chain guide in order to fix the problem completely? and is it much more difficult than replacing the upper timing chain guide?

Thanks,
Pat

[ 02-07-2002, 09:28 PM: Message edited by: pchio_s14 ]

Mav1178
02-13-2002, 03:22 AM
Originally posted by pchio_s14:
Ok, first of all, these questions is for the DOHC timing chain problem.

...

The kit is about $400 total, but I think I don't need the whole kit to fix the rattling problem. Can someone tell me which parts I should get?

Also, do I need to replace the Lower timing chain guide in order to fix the problem completely? and is it much more difficult than replacing the upper timing chain guide?

<font size="2" face="Verdana, Arial[/img]A few days late:

Parts needed, as posted by SoCal LM Robert K. last year:

**************************
It has been requested that I post this information, so please archive it, it
might be useful in the future.

Well here is the list of parts needed for the replacement, originally posted
from A&W some time ago, I have updated all the prices/part numbers as of
March 8, 2001 when I bought them to replace my timing components. All
prices except both chains are from Courtesy Nissan with the 240 discount.
These prices are for a DOHC KA24DE.

The prices are as follows:
#13028-5B600 timing chain @ $52.19 --not Courtesy's price
#13028-53F11 timing chain @ $39.63 --not Courtesy's price
#13070-4E101 tensioner @ $53.22
#13070-AD503 tensioner @ $53.22
#08120-64028 Lower Ten/bolt @ $0.41
#13085-1E401 chain guide @ $11.46
#13091-53F01 chain guide @ $62.92
#08120-6355E Upper Ten/bolt @$0.48
All prices include the discount for the 240SX Car Club of America.

I hope this information is of some use.

Robert K
91 DOHC &lt;--without rattle now
*****************************

As for fixing the lower timing chain guide, that is NOT where the problem is at.

If you listen to where your rattle is coming from, 99% of the time it is coming from the TOP timing chain. The lower timing chain guide sits roughly where the water pump is. Most of the lower chain guide is actually lower than the water pump itself. If the lower chain guide was making noise, you'd hear it from that area.

Patrick, try to make it to the Buttonwillow track event in 10 days. I can help you diagnose the problem there.

-alex

[ 02-13-2002, 03:24 AM: Message edited by: Mav1178 ]

pchio
02-13-2002, 04:13 AM
Thank You!
Actucally, I have ordered the parts from Courtesy Parts already. But I just ordered the upper tensioner and the upper chain guide. Coz I checked my car, the noise mainly is from the upper part. And I think I may not need a new timing chain, coz it is not a wear item. I will try to take pictures on the process and post it up later.

Few more questions:
1) I decided to drain out the engine oil and coolant before I open up the valve cover, just wondering is it necessary to do this for just replacing the upper timing chain guide?
2) And r there something i need to be caution on open up the valve cover and replace the guide/tensioner?
3) Do I need to get a new valve cover gasket?

P.S. Alex, I probably will be there on 24th. So see you there! and I really appreciated for your help and your information! http://www.freshalloy.com/

[ 02-13-2002, 04:21 AM: Message edited by: pchio_s14 ]

**DONOTDELETE**
02-13-2002, 08:08 AM
once it gets enough slack, the straight guide goes. especially if it's the old plastic type. once that happens the chain will be slack for the first 10 or so minutes of driving, you'll hear it. it will jump around and hit the front cover. it doesnt CHEW through the front cover, it CRACKS it and i'm guessing the sucker will evenutally shatter rather than be sawed through. and you can't quite see it if you just take the valve cover off (i mean the front cover damage, you should be able to make out a shattered guide).

NO...it will SAW thru to front cover.....
new owner here, had the motor apart....let me see if I can recreate the sequence of events....
1) Many miles ago (motor has 150K) the right side guide broke (most pieces ended in oil pan).
2) Chain began sawing thru front cover.
3) Couple of valves starting getting "hot" due to variable valve timing http://www.freshalloy.com/
4) Chain completes the sawing of the front cover, creating a leak in the water channel of the front cover. (here is where things getting a little confusing, normally this would lead to WATER in the OPL and an instantaneously dead motor, luckily that is not the case) Either way some coolant disappears.
5) Engine gets pretty damn hot...but hmmm. the vents do not produce any heat....hmmm (very little coolant flow)
6) 3 valves "burn", head gets hot, warps a little more than 12/1000 in the center.
7) High pressure oil channel feeds oil into cylinders 2 and 3, and into the water. Exhaust gases from 2 and 3 feed into coolant flow.
8) Pull everything apart, diagnose head problems...get head fixed....decide to change timing chain......
9) Become the official owner of the car as I convinced the previous owner to go and buy a spec-V at the same price I bought one 3 months ago.
10) Notice the absense of chain guide, pull oil pan and clean out the pieces...install new chain, notice hole in front cover, get hole welded
11) Finish installation, and the motor starts right up on the first try!!!

12) Slightly crack thermostat cover upon re-installation using a 1/4 ratchet...bummer....anyone have one?

13) Need to buy new oil pump and change it too!

Hank
89 240sx
02 Spec-V
72 510
87&88 Xr4ti (for sale)
98 F150 tow vehicle

**DONOTDELETE**
02-13-2002, 10:41 AM
My timing chain was replaced not TOO long ago. I cant imagine my timing chain failing within 30k, just doesnt make sense. When I pulled the cover everything looked ok, no adnormal wear on my guides.

Anyway, I was thinking I may try to upgrade the spring inside the tensioner.. try to make it stiffer. I'll eventually figure something out. BUT, as it stands.. my startup rattle doesnt seem to be anything too dangerous. But when my chain rattled constantly 2 years ago, I changed it immediately. Dont change it when it constantly rattles - expect some serious damage to your motor!

- Mike

**DONOTDELETE**
02-13-2002, 09:39 PM
how can it possibly "saw" through the front cover. it will only reach the inside of the front cover if it bends and flails outward so it impacts against the aluminum, it's not dragged across the surface. When i took my front cover off there was a spot on the coolant passage from the pump where it was hitting, it wasn't indented much or anything, no scrapes or gashes except for a little disturbance but there were plenty of cracks. i guess it depends on your definition of sawing. either way, it's not good for the front cover, i'm sure that we can all agree on http://www.freshalloy.com/

**DONOTDELETE**
02-14-2002, 08:19 AM
how can it possibly "saw" through the front cover. it will only reach the inside of the front cover if it bends and flails outward so it impacts against the aluminum, it's not dragged across the surface. When i took my front cover off there was a spot on the coolant passage from the pump where it was hitting, it wasn't indented much or anything, no scrapes or gashes except for a little disturbance but there were plenty of cracks. i guess it depends on your definition of sawing. either way, it's not good for the front cover, i'm sure that we can all agree on
<font size="2" face="Verdana, Arial[/img]Well...you saw all the nice little "hits" by the chain. now imagine it doing that for say 50K miles....Whereever it hit more often there was a nice groove. on the "top" side of this long groove it was about 5mm deep, deep enough to create a pinhole intot he water passage.
To me that seems like a good working definition of "sawing through to front cover"

Hank