Losing Coolant

[oldchieft]

Maybe a weakened head casting distorting under tightening loads?

Hairline cracking in the block, caused by hydraulic stress of bolts into the blind holes of the block?

Always check the is no oil or grease lying at the bottom of blind holes, to be extra sure put a thin cut along the thread of the bolt or stud. Most threads have enough clearance for this not to happen but very close tolerances can give this problem.

Jon the Chief

[rgh0]

Unfortunately, I have to bring this post back up. I replaced the original bolts with ARP and retorqued to 70. No joy. Had the head gasket replaced along with switch to QED 360 cams in early 2013. The shop checked the head and said it didn't need to be skimmed. Seemed fine when I got it back. Didn't put many miles on the car, so didn't retorque. Had the car painted last year, getting it back late this fall, so no significant mileage. I generally start it and let it warm up every other week over the winter. Started it up today and it came up to temp. Turned it off and noticed coolant at the back of the block. Oil and coolant look fine. No milk. Same symptoms as before. I will retorque head bolts up to 70 in sequence tomorrow. Any thoughts and suggestions. Dan

Sound like the head gasket is leaking again. It is heat cool cycles rather than miles that require retorquing of the gasket and it sounds like you have done a few of those.

cheers
Rohan

[collins_dan]

Retorqued to 70 and significantly reduced flow. The back two bolts seemed looser than the others. There is still some moisture build up along the back edge of the block. Should I torque to 75? Thanks, Dan

[rgh0]

If its still leaking after retorquing to 70 I think I would replace the head gasket..

cheers
Rohan

[collins_dan]

Ok, for future reference, how many heat cycles until I should retorque head bolts? I had always heard 500 miles, but I guess that is not a good metric for low mileage cars. Thanks, Dan

[rgh0]

Hi Dan

I normally retighten the head bolts as follows:

1. After the first heat cycle when the engine is first started and run.
2. I will then retighten after I have run in the engine, normally a couple more heat cycles and maybe a couple of hours running and maybe 100 miles.
3. I will then check a third time after a few more hours and maybe 5 or 10 heat cycles which is typically around the 500 mile mark for a normally used car.

I normally see some small movement in checks 1 and 2 above. The third time any movement is rare. After that when ever I have checked I get no movement.

cheers
Rohan

[collins_dan]

Some problems just don’t like to go away. Apparently my retorque in 2015 did the job as I have not had any problems since… until today. Drove about 60 miles to local cars and coffee this am. Car ran great, mostly non-stop highway and temp was good. Noticed at one of the last lights coming home that a puff of smoke came out under bonnet. When I pulled in the garage, popped bonnet and could see the coolant puddling on the back sides of block and top of gearbox. Letting it cool before further investigation. I did change to ARP head bolts when this happened before, so thinking I will follow Rohan’s guidance loosen 10 degrees, then retighten an additional 10 degrees, but not going over 80. Fingers crossed. Any feedback on this plan welcomed. Thanks, Dan

[2cams70]

For clarification - Did you use the ARP bolts or the ARP studs?

[mbell]

I'd take a careful look at the head for cracks around the bolt heads. Not unknown for them to crack and loose compression with a older head going soft.

[collins_dan]

ARP bolts. Loosened and retightened to 80 last night, but haven’t driven yet. The one bolt in the back right corner looking at it from the front is where the leak was. It was looser than others. Not sure why that bolt seems to loosen over time. Thanks, Dan

[2cams70]

ARP bolts. Loosened and retightened to 80 last night, but haven’t driven yet. The one bolt in the back right corner looking at it from the front is where the leak was. It was looser than others. Not sure why that bolt seems to loosen over time. Thanks, Dan

80ft/lb is too much. Should be 65 ft/lb. You risk distorting the head, block or both. If I were you I'd lift the head and replace the head gasket. You have already over compressed it so you now can't just back the bolts off to the correct figure.

[nmauduit]

ARP bolts. Loosened and retightened to 80 last night, but haven’t driven yet. The one bolt in the back right corner looking at it from the front is where the leak was. It was looser than others. Not sure why that bolt seems to loosen over time. Thanks, Dan

I don't want to be sounding ominous, but a head bolt getting loose would call for scrutiny for me, not something to push under the carpet by overtightening...

[rgh0]

I dont see retorquing head bolts as pushing a problem under the carpet. Gaskets compress over time with heat cycles and load and if retorquing them can reseal the gasket thats fine. If it does not then you have to ultimately replace the gasket but you lose nothing by retorquing first.

It appears to just be a water leak externally and that the fire ring is adequately still sealing the cylinder

cheers
Rohan

[nmauduit]

I dont see retorquing head bolts as pushing a problem under the carpet. Gaskets compress over time with heat cycles and load and if retorquing them can reseal the gasket thats fine. If it does not then you have to ultimately replace the gasket but you lose nothing by retorquing first.

It appears to just be a water leak externally and that the fire ring is adequately still sealing the cylinder

cheers
Rohan

what I see in this thread (granted, started more than a decade ago) is increasing and increasing the torquing, now up to 80, in attempt at fixing a leak over a long period of time, and I'm afraid that is shying away from removing the head for inspection while distorting it at the bolting points. A specific head bolt tending go get loose is bad omen in my book and would in itself warrant closer inspection. I'm sure you've also seen your share of damaged head from overtorquing...
I does make sense to properly torque and check said torque (esp. after rebuilding, it's actually in the manual...), but using overtorquing looks a lot like a "quick fix" to me here, and I'd be surprised of a durable outcome.

[collins_dan]

Thanks for the advice. Prior owner had overheating problems with the original head. Found it was cracked, so bought this head on eBay. It was rebuilt when I bought the 20 years ago and has always run well, only issue being the aforementioned leak. The head will likely come off this winter to investigate, plus address other items: lower compression on cylinder 1, gear box leak… just generally looking things over as it’s been 20 years.
All the best, Dan