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Discussion Starter · #1 ·
2008 Enclave cxl. The vehicle had no other problems except the timing.

Replaced timing chains, water pump, camshaft actuators and belt.

When we were topping up the coolant after the repair, it started dripping out the oil drain plug. There was a minor coolant leak at the water pump before the repair but nothing else.

Obviously have to tear it down again *ugh... Is the RTV gasket around the pump where we screwed up? We used Permatex ultra black. There was a little washer/o-ring that came with the timing chain kit we couldn't find a spot for, I dunno. The sensors and actuators all had new o-rings. Very frustrating.

Appreciate any insight.
 

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my engines out in the garage. i redid the oil pump and chains last weekend. my kit was cloyes. chains, tensioners and guides only. abbreviated kit. no gaskets in my kit.

the only seal associated w coolant i can recall is water pump.

i redid the seals on the newer tranny i bought. rear main done. swapping tcm/valve body, the off to oil pan and i’ll be to the timing cover. will let u know if i see anything.

let me know if u figure it out and can give any tips

i feel for anyone doing this w engine in car. not a lot of room clean and properly rtv the timing cover
 

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Discussion Starter · #3 ·
Well, we took the timing cover off again and used Permatex Ultra black to redo the gasket. Still leaking, pouring water in the radiator to almost full and within 10 seconds it starts dribbling out the oil drain plug.

Could the cylinder head have shifted? Could the gasket somehow blown while doing the timing chain job? I don't even know how to pin point where the leak could be. Should we remove a cylinder head? It has to be the timing cover somehow, I don't have enough experience unfortunately to figure it out.

I know already if I take it to a shop it's going to be $100 for a tow and 2-3 grand just for the mechanic to redo the timing cover, figure out what the problem is and put everything back together. I paid $1000 knowing about the timing chain. Was planning on giving it to my daughter I do not know now...
 

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It’s got to be a pretty significant leak for a non-pressurized coolant system to have coolant finding it’s way into your oil pan. Any time I’ve seen coolant in oil it’s been a blown head gasket or a damaged head/block. A bad oil cooler can mix oil and coolant as well. It that’s pretty rare. All of this seems unlikely to have happened while you were making your repairs though.

I guess I’d start with a leak down test on each cylinder. I’d do a leak down because with your oil issue I wouldn’t want to be cranking the engine as much as you’d need to in order to compression test all 6 cyl. I suppose you could drain the coolant and then fill the oil before doing the compression test.
 

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I want to follow this ... what an odd problem.
 

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i’m sitting here ready to put my timing cover. the wp interface to the block is a fully casted feature. no parting lines.

could that spare oring u mentioned be for the oil pan pick up tube? there’s no other rubber seal related to coolant beyond the wp seal

dumb q, but did u instal the water pump gasket between the timing cover and block?

another dumb q, did u tighten the timing cover just enough to ooze out the rtv, wait an hour, then full torque?

was work done w engine in car? harder to do...

my interface between heads and block right at the timing cover interface has a little gap. i need to put extra rtv there. but that’s oil, not coolant

what’s ur ownership history? did u just buy the car?

back in my FAL days on the production line, a 10x jewelers glass was my best friend. just enough to see imperfections in parts not seen w naked eye

we always used mek to wipe sealing surfaces in aerospace. mek removes contamination, not just smear it around like ipa and acetone. i lightly sanded my surfaces then mek wipe



there’s the coolant outlet tube above the wp. did u replace those seals? if those leak, coolant would rest at that interface between heads/block i mentioned before. if that interface leaked, that’s a coolant leak path

does this car have an oil cooler? i just reinstalled my oil filter adaptor plate w new seal. i didn’t pay attention to notice a coolant jacket there

compression test and post.....
 

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Discussion Starter · #7 ·
I'm sitting here ready to put my timing cover. the wp interface to the block is a fully casted feature. no parting lines.

could that spare oring u mentioned be for the oil pan pick up tube? there’s no other rubber seal related to coolant beyond the wp seal


I've gone threw the service manual and the washer doesn't fit anywhere on timing cover.

Dumb q, but did u install the water pump gasket between the timing cover and block?

Yes. It's an aftermarket gasket, not GM or AC. It's a snug fit and with the RTV around the outside I assumed it would be enough. I have an AC Delco ordered now just in case.

another dumb q, did u tighten the timing cover just enough to ooze out the rtv, wait an hour, then full torque?

Yes. Finger tight. Left it for 2 hours. Torqued the bolts in the proper sequence and NM + the 60%. We used grey permatex the first time. Ultra black the second.

was work done w engine in car? harder to do...

It was.

my interface between heads and block right at the timing cover interface has a little gap. i need to put extra rtv there. but that’s oil, not coolant

Yea, I saw that. Finger nail just catches it but won't fit in and you can see the head gasket. We straight edged it and the level was good. 0.000

what’s ur ownership history? did u just buy the car?

The car was recently purchased, yes. Previous owner didn't want to bother with the timing chain. I drive an Avenir now but had a 2012 Enclave previously.

back in my FAL days on the production line, a 10x jewellers glass was my best friend. just enough to see imperfections in parts not seen w naked eye

we always used mek to wipe sealing surfaces in aerospace. mek removes contamination, not just smear it around like ipa and acetone. i lightly sanded my surfaces then mek wipe



there’s the coolant outlet tube above the wp. did u replace those seals? if those leak, coolant would rest at that interface between heads/block i mentioned before. if that interface leaked, that’s a coolant leak path

The 2 gaskets there were changed. There isn't actually a path for the coolant to enter the timing area even if it leaked but I understand what you're saying.

does this car have an oil cooler? i just reinstalled my oil filter adapter plate w new seal. i didn’t pay attention to notice a coolant jacket there

compression test and post.....

One other thing, when we removed the water pump and gasket off the coolant poured out but the coolant had already stopped leaking from the oil plug so The leak has to be above that area right? Gravity and all. I'm not sure of the passages coolant takes thru an engine tho.
 

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i’m no expert on this car.

go w the previous guys suggestion and check cylinder comp

as i just installed my timing cover an hour ago, i just don’t get how a coolant leak can happen there w all uv done. twice

i don’t know where an engine oil cooler is on this car, mines 2009, normally they’re at the oil filter on cars i’ve worked on. maybe 08/07 MY is different?

no way those heads will move and break seal on a timing job.
 

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if ur going to tear down again and replace the wp all rubber gasket between block and timing cover w gm part, use the old gasket w rtv and screw it down w a piece of plexiglass. w timing cover off and refill the coolant. that’ll confirm ur timing cover job is good? science project. not sure if it’s worth it

sounds like head gasket
 

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Discussion Starter · #10 ·
Found it...

The right side coolant passage behind the water pump had a crack about 1/4" long right at the front. We cleaned it with a dremel and put 3 expanding layers of JB weld on it, sat it for a day and...no more leak. Anything deeper and we were screwed, thank god. We think the timing cover bolt or the 18" upper engine mount bolt was way over-torque and split it. Maybe, maybe not.

I know it's not the greatest fix but it'll just have to hold 15-16 psi and coolant. Should last for a couple years otherwise the engine is garbage. Engine runs better now. Oil change #3 tomorrow (still trying to get the coolant out.)

Appreciate all the help mate, your plexi-glass idea sent us in the right direction.
 

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wow! a buddy of mine had a crack in the lower unit of his mercury outdrive by the propeller. jb welded it. been holding for five years. our field techs used it in iraq to seal bullet holes to hold nitrogen purged electroncs. it’s a unique product. i like how u think!

thnx for passing on the root cause and fix
 
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