Possible blown head gasket

Flyin Brian

Flyin Brian

Member
Joined
Jun 18, 2011
I think I know the answer but here goes. Recently freshened motor, cometics, arp bolts. About 20 psi boost no knock but suddenly got the loud farting sound from under hood. Lifted immediately. No water in oil, no oil in water. Car runs fine but when I pull the driver side valve cover breather with the motor running I hear a pffft, pffft, pffft sound that it did not make before. Checked compression and all cylinders are between 170 and 180. Should I borrow a leak down tester or should I just start tearing it down? Did not catch it on a log. Spark plugs look ok. No visible head gasket damage where I can see it. Suspect a minor leak on the intake side of a cylinder but hate to tear it down again. I guess re-torque would be a waste of time at this point.
 
Do you hear a light hiss when you shut off the engine. Mine did. Slight leak into the valley at #3 and #4. Mine ran fine and had good compression but down on power under boost.
 
How is your EGR blocked off? Exhaust could be leaking.
 
Pronto said:
Do you hear a light hiss when you shut off the engine. Mine did. Slight leak into the valley at #3 and #4. Mine ran fine and had good compression but down on power under boost.
Click to expand...
I will listen for that next time I fire it up and turn it back off.
 
Using any oil? How's spark plugs look? Mine blew off the vac line at the throttle body for the regulator, went lean and damaged a valve guide. Compression test showed OK, but it was using a lot of oil and fouling a plug
 
Check your intercooler and up pipe hoses. They can make funny noises under boost but not show "at rest". Especially if they are thin stock type couplings.

I like to "borrow" the wife's hair spray for install. It lubes for easy hose slip on then turns sticky to hold it in place.
 
Not using any oil. Spark plugs look fine. Boost hoses look ok. Think I will borrow a leak down tester. That should definitely show the problem. This bites.
 
Probably a cracked piston if you can feel compression coming out of the valve cover


Sent from my iPhone using Tapatalk
 
bison said:
Probably a cracked piston if you can feel compression coming out of the valve cover


Sent from my iPhone using Tapatalk
Click to expand...
That would bite even worse! I really hope it is not that. I put my hand over the valve cover hole and could not feel it but could hear it.
 
Pulled the heads tonight. Number 1 blew to the intake side. Everything else looked ok. Going to get the heads resurfaced and put it back together.
 
Here is a picture. It totally torched the head gasket. Burned a notch out of the first layer of the gasket. I did not catch a log as my data logger always seems to disconnect when I approach full boost.
It happened around 20 psi. It was rich enough on the way up and there was zero knock. Knock gauge never even beeped once. I did a torque check, which is probably not that valid, before taking the heads off. I marked each head bolt at 12:00 and backed each one off in sequence and re-torqued with a calibrated torque wrench. None of the bolts turned any farther than where they were. I had got the motor hot a few weeks prior accidentally due to a bad radiator. Temp only got to about 250 before I shut it off. Temp was under 200 when the gasket let go. I checked the head surface and it is not perfect. Can see minimal daylight under a real straight edge in a few areas but not enough to get a .0015 feeler gauge under it. Block is very flat and smooth.
head gasket pic.jpeg
 
"I checked the head surface and it is not perfect."

It looks like you found the problem. The head might warp even farther when it gets hot.

I wouldn't use that head anymore. I'd get two new heads,but I tend to overkill on things.

Some would plane both heads and consider them heat-cycled.

Sorry to hear you had to tear it back down again.
 
I am gonna run the heads by the machine shop today and see what they say. If I had a pile of money I would get a nice set of aluminum heads but that not in the budget right now. I have another set of irons laying around somewhere but they need work.
 
Thats a bitter pill. Burned right through where the missing head bolt would be.

Were the heads and block re surfaced when you built it?

I would definitely ditch the bolts and get some studs.

I have some low mile stock heads laying around. If you need one or both, you can have them. Just pay shipping.
 
Thanks TurboBuRick. I wish I had those missing head bolts!
When my old machine shop built it 6 years ago they surfaced the heads but not the block. I blew a head gasket on number 6 a year ago but it ran lean and was pulling 8 degrees of timing at 25 psi boost so I figured that one was my fault. I did the assembly this time around. ARP head bolts with ARP lube. Torqued short ones to 75 and long ones to 80. I used RTV on the threads since they go into the waterjacket. Did not re-torque. Might do studs this time around. Are they really that much better? I hope I can save these heads. Got a lot of money in them. EGR filled, port match, all the bowl work, valve job, etc. I guess I could still use my K-motion springs and Ferrea valves in a different set of irons if my castings prove to be bad. I asked the shop to CC the chambers as I do not know how many times these heads have been cut in the past.
 
Classic #1 hole failure. That's from detonation/pre-ignition. 1 is usually the leanest
 
You must log in or register to reply here.

Similar threads

Paulmac201
Head Gasket Failure
2 3
Replies
40
Views
1K
Dylan4570
D
O
Oil Pump Locked Up
2
Replies
24
Views
2K
TIMINATOR
TIMINATOR
L
Stock replacement turbo
Replies
6
Views
916
Anthony P
Anthony P
6gunn
intake manifold gasket problems
Replies
5
Views
2K
Chuck Leeper
Chuck Leeper
H
AC CONDENSATION LEAK
Replies
5
Views
708
Chuck Leeper
Chuck Leeper
Top