Head Gasket?

[samandw]

1987 GN. has coolant coming out of headers. I did a compression check with all plugs out. 1,3,5 120,120,120 2,4,6 119, 115, 112. seems ok to me? (im at 6,200ft elevation) also did a cooling system pressure test held 16psi. started it up let it run and it built cooling system pressure like it is supposed to. there's no coolant in oil or oil in coolant. and i didnt see anything abnormal on the plugs (at least to me....what does burnt coolant look like?) thoughts?

thanks

 

[buickboy]

Compression should be near 155-160 with no more than a 10% variance between cylinders

 

[samandw]

Should i just go on the assumption that its head gaskets? i want to get the thing at least tore down this weekend if i need to go into it that far. what are your guys thoughts? anything else it could be?

 

[samandw]

ok so i pulled the intake manifold off. everything looks solid. gasket wasnt tore or anything like that. no visible cracks on intake or sides of the heads. what are your guys thoughts?

 

[JoelGN]

A slight warpage of the head at the right place could be allowing some exhaust gases to enter a coolant passage and, at the same time, be sucking some coolant into the combustion chamber. This can sometimes occur and not show up testing compression. Have you checked your radiator overflow tank for a layer of carbon at the top?

 

[samandw]

at the top of the overflow tank or at the top of the coolant in the overflow tank?

 

[SHADOWII]

is it possible ...

that you could have over-boosted? if you lifted the head, you could have put a crack in an exhaust port, especially if the walls were ported too thin do to core shift, etc.

 

[samandw]

last time i drove it the up pipe to turbo gasket was already blown out so it wasn't making full boost. I never saw it go above 22psi. but i guess if the alky injection didn't spray on a hard pull it could have got some detonation?

 

[Just a Six??]

On the compression test was engine warm & TB fully open? You can get skewed numbers on a cold engine & TB closed.

 

[JoelGN]

at the top of the overflow tank or at the top of the coolant in the overflow tank?

Thin layer of black floating on top of the coolant in the overflow tank.

 

[samandw]

On the compression test was engine warm & TB fully open? You can get skewed numbers on a cold engine & TB closed.

No and No

and Joel i didn't see anything floating in there.

but i tore it down anyway just to see what the insides looked like. the head gaskets looked fine and there where no visible cracks.

somebody mentioned to me it could be the water pump spraying out of a weep hole or bypass hose on to the header right by the up pipe where I saw coolant?

guess I'll replace the water pump while I'm in there.

 

[JoelGN]

Sounds like you're leaving no stones unturned. Be sure to have a reputable shop resurface the heads prior to reinstall because they definitely are slightly warped. Best of luck. Joel

 

[samandw]

well if I'm gonna do it i mind as well do it all the way Iv'e heard some arguments about resurfacing the heads without resurfacing the block that it can leave you with a uneven surface? what are your guys thoughts on that. I'm planning on taking the heads to a machine shop and having them do a valve job and check it for any cracks , also I'm gonna just have them check to see if its warped. I was thinking if it has some serious warpage I should get them resurfaced but if its not very bad i think i'll just leave it.

 

[turbofabricator]

Sam,
Replace the head bolts, too. ARP. I have a couple sets at the shop if you need them right away. (or are you away from home?) I also have a tool steel straight edge to verify deck warpage. If it is not warped, leave them alone. PM me for my number.

 

[84BuickGNYorkPA]

Sounds like the source of the leak is still in question. Take a close look at the freeze out plugs, I've seen them rust through(pin holes) in the past. (Early 1980's but still)

Chuck

 

[samandw]

I will check on the freeze plugs for sure. however should I pull the timing chain cover? it looks like to me right behind the water pump that the coolant goes through that timing chain cover into the block? and there is a gasket behind that. is there any chance it could be leaking out of that gasket? I know i should have done some more diagnosing before tearing into it. but while I'm hear I mind as well fix anything that might be the problem. also how can I get a torque wrench to that back side passenger head bolt?

Thanks

Ken, again thank you for the offer. I replied to the valve job post about the car not being in WA.

 

[samandw]

Are those freeze plugs anywhere near the up pipe to turbo gasket? cause pretty much all the coolant I saw was coming around that area and it looked like it was kind spattering from somewhere very near that. at the time I thought it was just coming out that up pipe to turbo gasket cause i had just finished replacing that. so I thought the vibration of the exhaust was causing it to spatter.

 

[84BuickGNYorkPA]

Well now that we know that Ken (turbofabricator) is your brother, I'll just step out of the picture. There is a gasket of course between the front cover and the block and yes coolant going to or comming out of the water pump, it's the "main artery", probably the best place to start.... Ken will tell you like it is, lucky you having him for a Brother.
My 5 Brothers all look at me funny for driving a 26yr old car.... something about growing up.... I don't pay any mind to them :wink:

Chuck

 

[samandw]

hey sorry about the confusion... this is Sams brother. he told me just to use his account cause I'm working on the car so it would be faster then relaying everything my bad for the confusion guys.