Oil leak side cap bolt

[akrockhound]

This is a known issue and I have to get it fixed every year - actually about every 9 months.

The problem is one of the side cap bolts on the lower drivers side of the block leaks oil. My mechanic explained that the head of the bolt does not have the right shape for the seat. There is a GM bulletin (about 4 yrs old though) on the issue that explains that the fix is use a new bolt, add bolt seal, let it dry and re-install........

My question is whether there is a newer/better fix for this issue. When I brought the bulletin to the dealer and asked him to call GM and see if they had a real fix yet he said he could not call them unless he had my truck in the shop and an RO open...For me it is a hassle to do this and I don't want them to even touch my truck right now because 2x they have mis diagnosed this problem as a leaky front oil pan and keep the truck for weeks without fixing the leak (long story but read - my dealer sucks!!!!).

Does anyone know of a better fix for this problem?

[DmaxMaverick]

I'm not sure which "bolt" you mean. If it is a bolt, replace it with a flang-head bolt and use a copper washer (or nylon if the torque is very low). Both can be had at any hardware store. Seal the threads with Loc-Tite anaerobic thread sealer, and it should never leak or loosen.

[akrockhound]

It is the main bearing side cap bolt - The torque setting is 52 ft-lbs.

The GM document that describes the problem and ineffective fix is document #1575652

[DmaxMaverick]

Aha! You didn't specify the engine, and posted it up near the 6.5 forum (I'll move it to the Duramax forum). My mistake.

Same thing, only use the original bolt. And, I'd use a brass washer (harder) to withstand the torque, and use the Loc-Tite anaerobic sealer on the treads. Use 10% less torque to compensate for the lubrication of the thread sealer and washer. You can use some sealer at the bolt head/washer, which may help. It shouldn't leak (I haven't heard of one), but that doesn't mean it won't. Obviously, it does.

[JohnC]

Counterbore the hole an put an o-ring around the bolt: should stop any leaks.

[DmaxMaverick]

OK. I've had some time to look further into this. If the correct bolt is used and torqued properly, it should not leak. The only bulletin I was able to find addresses correct bolt identification and use. There are 2 possible bolt sizes, and the difference is only 4mm (less than 3 threads), but is critical (I'll list the bolts below). If the wrong bolt is used, it can bottom out in the counterbore, and torque can be reached before the head gets full engagement. This could cause a leak. If the tolerance is very close, it may take some time before the leak is present (like 9 months), while the bolt may appear to be torqued properly. Bolt selection is also specific to casting dates. The breaking date is August 15, 2005, so unless your block has been replaced with a later model (after this date), it should use the "shorter" bolt. If the dealer (or you) replaced the bolt, it is entirely possible the wrong (longer) bolt was used. There could have been an initial defect which started it all, so if you are using the original defective bolt, or the wrong replacement bolt, it could explain the issue you are seeing. The bolts can be identified by the head, without removing them. The longer bolt (M14x109, for later castings) will have a raised circle (button) on the head. The shorter bolt (M14x105, earlier castings) will have a smooth/flat head. If you are using the shorter bolt, and it still leaks, you may have a defective bolt, defective block thread or counterbore, or a defect in the block casting. If the leak continues with the correct bolt and torque, I suggest either, having the bore/thread/casting examined, or seal it with the procedure I described above (with a brass washer). Going further will likely cost more than it's worth, and as long as it is torqued, and stays torqued, it should not cause any serious problem.


TSB # 06-06-03-003
Date: January 20, 2006


Early style bolt (before August 15, 2005):
M14x105
Smooth head surface
GM part # 97209622
GM list price $1.84

Later style bolt (August 15, 2005 or later):
M14x109
Raised circle (button, not ring) on the head
GM part # 98019464
GM list price $4.94

The part numbers are good in GM's current inventory.


Side cap bolt torque is 58 ft-lbs. with no specific torque procedure for the side bolts (once the primary mains are torqued properly).

[DmaxMaverick]

Counterbore the hole an put an o-ring around the bolt: should stop any leaks.

That would work to stop a leak. However, we need to verify the bolt head is being torqued against the block casting, and not the bore threads or counterbore. If it is getting full engagement against the block, it should not leak, in any case. The problem I see, is the bolt reaching torque before the cap is pulled against the inner block surface, allowing oil to seep between the cap/block surfaces, and out the bolt hole bore, and around the under-torqued bolt head. This is why just sealing it is a bad idea. We need to be sure the bolt torque is being applied to the correct surface(s).

[More Power]

Great info DM!

My question is - how bad is the leak from one of these side cap bolts? If the crankcase pressure is normal, there shouldn't be any force within the crankcase that forces oil past a side cap bolt.

Might be a good idea to measure crankcase pressure....

Jim

[DmaxMaverick]

Great info DM!

My question is - how bad is the leak from one of these side cap bolts? If the crankcase pressure is normal, there shouldn't be any force within the crankcase that forces oil past a side cap bolt.

Might be a good idea to measure crankcase pressure....

Jim

Excellent point. There should not be significant positive pressure in the crankcase. And, the main caps should be above the sump oil level. If the leak is significant (more than just seepage), there is possibly a more serious underlying problem.

[JohnC]

...However, we need to verify the bolt head is being torqued against the block casting, and not the bore threads or counterbore...

Agreed! (Silly me, I just assumed the right bolt was in place...) In fact, if the bolt bottoms out then it might as well not be there at all... Just cork the hole! ;)

[akrockhound]

I have attached the GM document and a copy of the repair on one of 4 occassions it was made.

I notice the bolt number on the repair order does not match either of Mavericks.

I will run your solutions past my mechainc (not the dealer) with the hope of fixing this (finally) once and for all.

regarding the question of "how much" is it leaking. Well enough to form drops of oil on the bottom of my front differential, but not enough to ntice a change in oil level on my dipstick over a few weeks. I just like a clean/tight machine....Like i said the frustrating thing is that I shoudl be able to get this fixed if I could only have a reasonable conversation with the actual mechanic at the dealership instead of going through the damn service writers.

Even though it is a warranty issue I am tempted to take it to an independent diesel shop where they will take the time to read all you comments and help to a successful conclusion.

[SoTxPollock]

Hey if its because the bolt too long, why not pull the bolt out measure it and buy a nut that will fit the bolt, put the nut on and then grind off the excess length, when you remove the nut it will clean the threads on the bolt so that it will go right back in and not bottom out inside, if that is the original problem. That approach has always worked for me if the bolt I had was too long.