Head Leak #4 via Leak Down Test

[DRACO A5OG]

Hey Fellas

So I was diagnosing a sudden power loss issue on acceleration.

Did a Compression Test, PSI results, dry/cold 57F ambient:

#1 170
#2 173
#3 174
#4 95
#5 160
#6 173

Wet tested #4, PSI went up 5 PSI to 100. Not too happy with #5 either, I can see both head to cam seam appears to be weeping oil ( wet ), nothing at crank. So hopefully rings are intact.

The leak down, per OTC instructions:

Warmed her up for 20 minutes at 2000 RPMs ( observed allot of popping ), til warm.

Removed Oil Filler Cap
Removed Air Filter
Placed on #4 TDC
Connected Leak Down Tester and brought Air Compressor up to 100 PSI, dialed OTC regulator to 90PSI



Yay! 58% LEAK (38/90)



No air leaking from Oil Filler, Air Intake Box nor Exhaust, WTF

Wait a minute, I hear air from the Fan Housing, yeah that makes sense, no radiator, so that is our version of a Radiator Leak ergo Gasket or Head Leak ( On Video at 0:23 )

Time to drop the engine, Happy Days

[DRACO A5OG]

Now to ponder, Repair, Top End Rebuild or Complete??? Oh the Joy!

[75 911s]

It's only money. But sorry to see this man. Hopefully you can turn it into a fun winter project.

[DRACO A5OG]

Indeed.

Well, I see no gaskets from head to cam tower, so it must be either the sealant gave way or I have cracked head, More Joy

[zippy_gg]

How man y miles on your 85 Targa?
This may help with your "complete or just top end" decision.
Either way I'll meet you on Saturday with the engine stand and yoke.
Sorry to hear about your troubles Brother Jim...

[BK911]

I had the same issue on a 3.0. Took off the head, lapped it to the cylinder, put back together and vroom vroom!! Good luck!!

[DRACO A5OG]

Originally Posted by BK911

I had the same issue on a 3.0. Took off the head, lapped it to the cylinder, put back together and vroom vroom!! Good luck!!

Can you provide more details or direct me to a thread, regarding "lapping"?

If you meant by the Valves, oh yeah, it will be sent to professionals for that work :-D

[Rawknees'Turbo]

Originally Posted by DRACO A5OG

Indeed.

Well, I see no gaskets from head to cam tower, so it must be either the sealant gave way or I have cracked head, More Joy

Correct - no gasket (sealant only) between heads and cam carrier, but there isn't any place for compression to leak there, anyway.

I don't know what to make of your hearing hissing coming from the fan housing other than for a crack in a head or cylinder (would probably have seen a fair amount of oil in that area, though), or very poor sealing between a head and cylinder form a broken head stud, etc . . .

[DRACO A5OG]

^^^ yeap, I am preparing for the worst.

Yes, I have observed allot of oil on top when I had pulled the alternator and recent cam swap on the lower side. At first I thought it was leaking rocker shafts, but nope those were bone dry after swap.

[dad911]

Head Studs OK?
Miles?
Prior rebuild?

[Tori]

Sorry to see that Jim,..... whens the engine drop party ? I think i have some leftover undrunk (drank?) beer.

[DRACO A5OG]

Originally Posted by dad911

Head Studs OK?
Miles?
Prior rebuild?

Head Studs, not sure yet, but I believe so but I will soon discover on tear down.

Miles, allot, over 316,000

Prior rebuild 150,000 miles ago, I got her at 170,000+/-, Wow I put allot of miles on her since 2005

Side Bar:

I am surprised how well the D-side & #6 compression came out, I thought that side & #6 got more extreme temps, guess not.

[DRACO A5OG]

Originally Posted by Tori

Sorry to see that Jim,..... whens the engine drop party ? I think i have some leftover undrunk (drank?) beer.

Happening tomorrow morning, I hate dropping at night, my old eyes can't see poop. Don't get old Brother Tori

[DRACO A5OG]

[Rawknees'Turbo]

^^^

Brother Dracolio - will be fascinating to see what you find - the oil leakage makes me think broken head stud(s), but those aren't usually associated with sudden power loss (unless several broke at once, which doesn't seem likely). Did you hear a bunch of "pffftttt pfffftttt" noise from the engine the last time you ran it (as in, actually hear combustion leakage while the engine was running)?

[DRACO A5OG]

I think I did when power was lost on accel.

[jlex]

Damn.... didn't you just finish overhauling the transaxle on that car? Bad luck. At least you've got the know-how to delve into a project...

[BK911]

Originally Posted by DRACO A5OG

Can you provide more details or direct me to a thread, regarding "lapping"?

If you meant by the Valves, oh yeah, it will be sent to professionals for that work :-D

Just like you would lap a valve in a head, but instead you lap the cylinder to the head.
Basically put some lapping compound around the cylinder, insert cylinder on head, and start spinning back and forth.

On my 3.0, I didn't notice any power decrease. But it was in a 2150# coupe. Only indication was a puff of smoke off throttle. Did a leakdown and heard air escaping from the fan. Just like you. When I pulled the head some of the gasket was actually deformed and *leaking* past the head cylinder interface. I will try to find a pic but that was several computers ago.

Good luck!!

[DRACO A5OG]

Oh quite interesting, I never knew you could do something like that.

Outstanding!

Originally Posted by BK911

Just like you would lap a valve in a head, but instead you lap the cylinder to the head.
Basically put some lapping compound around the cylinder, insert cylinder on head, and start spinning back and forth.

On my 3.0, I didn't notice any power decrease. But it was in a 2150# coupe. Only indication was a puff of smoke off throttle. Did a leakdown and heard air escaping from the fan. Just like you. When I pulled the head some of the gasket was actually deformed and *leaking* past the head cylinder interface. I will try to find a pic but that was several computers ago.

Good luck!!

[DRACO A5OG]

Oh I see, what you mean now: