Blown Head Gasket! w/large pics

[Tooky]

After spending 12+ hours over the past few days, tonight I got my driver's side head pulled off to try locating the source of my low-compression problem and misfire problem. (See this thread for the history of this problem)

Here it is about halfway apart:

As soon as I got the head off, the problem was obvious within 1 second! :doh:

:crazyeye: :splat:

Boy I wonder what caused it!! I was datalogging at the time and the AFR was between 11.2-11.6 and the boost 16-21 PSI. Nothing unusual except it was my first and only WOT test ever driving around with Open Loop. (I always run Closed Loop except this one time.) I'm not ready to blame it on Open Loop since I can't find any lean areas but damn, some coincidence? I've pounded the piss out of this factory motor for 7 years and never had any problems, then I swap vortecs in with a cam and make a bunch of dragstrip runs, but suddenly when it hits 707mi on the new heads, a headgasket blows for no reason. :dunno:

Anyone got any tips on the reinstall? I'll know more when I clean the deck & heads. But assuming they look good, and I check em with a straight edge, would you just get a new gasket and bolt back together? The passenger's bank of cyls comp. tested 145 PSI so I don't have any reason to think that head needs to come off too yet. Although I was thinking of ceramic coating the exhaust manifolds..

Here's a pic of my vortec heads for you DIY porters out there, get a load of the exhaust mismatch. Tells you where to go heavier when porting the exhaust manifolds.

SyTys usually don't blow headgaskets, so I must be really lucky here! Especially blowing only one and not mixing any oil/coolant. Props to Dave Goodhue, David Van Hulst, and John Rue for guessing head gasket (in the prior thread).

Someone suggested the head "lifted" - I spent an eternity properly burnishing and torquing in sequence the ARP 6pt SBC Head Bolts when I did the heads & cam last fall. Why would the head lift? And why would I get so many drag runs with the same tune and no trouble? These are stock #5855 Victor head gaskets.

Bottom line, I'm glad it was just the head gasket. Cheapest part to replace! The edge of the pistons right between cylinders look a tiny bit scorched, white in the photos. Hopefully it's nothing too serious and this stock shortblock can go back into active street duty!! :thumbsup: :syty:

 

[unluckyty]

Re: Blown Head Gasket! w/large pics

Should hopefully just be the gasket only.

I don't know how likely Sy/Ty pistons are to crack in the ring land area (mine put a hole in #1 piston). In my turbo Dodges, when I had low compresion the piston would look fine, but be cracked in between the ring lands.

Greg

 

[JSM]

Re: Blown Head Gasket! w/large pics

Open loop had nothing to do with anything. Syty ecm doesn't run closed loop under boost anyways. With the code written as stock it can't.

I suspect gasket was weakened before, and just finished letting go while driving. Make sure head/engine is flat. Might just be a bad gasket.

What brand did you use?

 

[Foot Performance]

Re: Blown Head Gasket! w/large pics

I have been thinking of using multi layer steel shim gaskets I have seen them on just about every new engine and wonder if they would be good for out application

 

[Luke]

Re: Blown Head Gasket! w/large pics

do ARP's require a re-torque after several heat cycles?

 

[JSM]

Re: Blown Head Gasket! w/large pics

I have been thinking of using multi layer steel shim gaskets I have seen them on just about every new engine and wonder if they would be good for out application

I have MLS gaskets on my truck. Read a lot of good success with turbo guys using them.

 

[denny]

Re: Blown Head Gasket! w/large pics

Josh, how much deg timing are you runing?

 

[turbodig]

Re: Blown Head Gasket! w/large pics

Hmm... if it were just between 2 cyls, I'd write it off as fluke.

Since it was essentially between all of 'em, the theory that the head "lifted" slightly seems reasonable. Question is... why?

You did resurface your heads when you put them on, but you didn't do the block. There may be a slight low spot there that left less clamping force on the gasket.

Clean 'em both up really good, and check block deck flatness top to bottom with a really good heavy straightedge. Shine a light behind the straightedge to see how much light gets under the crack.

I've got a big, thick piece of steel that I wrap with some 320 grit, and make a few light swipes across the surface. The steel block has to be big enough such that it won't fall into the cylinder hole, and stays flat against the deck.

After a few swipes, the high spots are shiny, the low ones, not. Depending on how bad the lows are, will drive your decision on what to do.

If you still have good flatness, go with a new gasket and put 'er together. Instead of putting the sealant in the bolt holes, put the bolts in and torque 'em down, loosen, torque, loosen.
(ie, cycle the bolts a few times). Then put the sealant on there, and re-torque.

If you have a buddy with a torque wrench, check the bolts against that wrench. (to make sure your torque wrench isn't out of whack)

The one really big advantage to studs, is that you can put the sealant on the block threads, and still get a good torque reading (ie, one not affected by the sealant).
That being said, a lot of guys run bolts and do just fine.

 

[Don W.]

Re: Blown Head Gasket! w/large pics

X2,3,4 EVERYTHING that Dig said. It gonna be difficult to check that portion of the block but you have to be sure it's flat and true. Seriously consider taking the head(s) to a shop for a light surfacing. Then you'll know for sure they are true. Since you're this far along you should consider pulling the other head for inspection and gasket replacement. Cometic(sp?) gaskets for replacement? Can you do studs with A/C? If not studs then replace all bolts.

Could you be running lean on this side? How did the plugs compare?

 

[fivetodrive]

Re: Blown Head Gasket! w/large pics

I would really suggest head studs as well as everything that Dig suggested. The studs can be a little tricky to get the headson and off but they have a nice allen head in the top so you can still get them out with the head on.

It also looks like you had an exhaust leak on the top of Cyl#3... But it may just be the picture. If it is leaking maybe get the manifolds surfaced as well...

 

[Tooky]

Re: Blown Head Gasket! w/large pics

The heads were surfaced to better than 50RA when I put them on:

Here's a pic of the factory Victor Reinz 5855 head gasket I used when I did the Vortecs:

(All this is a rehash from my 100-photo Vortec Install thread but I'm sure it's a lot fresher in my memory than anyone elses! )

The head bolts, I spent hours and hours, chasing the threads, then doing 3 repetitions of 20-40-loosen torque sequences to each head. Then for the 4th and final sequence, I did 20-40-65. 65 per ARP's instructions in my head bolt kit.

When I cracked each head bolt loose with a breaker bar, they all "cracked" like a lug nut, and took some serious effort.

I will definitely check the deck and heads with a straight edge when I get em clean.

Denny, I was running up to 25.0* timing with a max of 4.6* knock briefly during spoolup (then it went to 0.0).

As for the exhaust manifolds, yes they were leaking horribly. I should have had them surfaced when I did the heads. I'm going to solve that problem this time around... Hopefully with no RTV.

I have been sitting on a set of Cometic head gaskets for about 4 yrs now. I didn't use them because I don't have the resources to get the block surfaced to meet their requirements.

 

[jwaller]

Re: Blown Head Gasket! w/large pics

do not port the lower portion of the exhaust port. it's that way for a reason. you dont have to get the block/head surfaces perfect for using cometics. most shops cant get them they way they want. I would run them. your surfaces look good but you need to have the block and heads checked for surface straightness after burning thru like that. you will have some amount of high/low spots after burning thru. all depends on how long and hard it was driven after it happened.

 

[It's just a six]

Re: Blown Head Gasket! w/large pics

Just wondering what you used for a straight edge?
It needs to be a tool just made for checking straightness, borrow one if necessary.
What type of torque wrench did you use,is it calibrated? Correct lube/sealant on the head bolts?
Theads in bolt holes where all cleaned up ? Did you run the bolts through prior to torquing them? Was there any drag on them?
Just something to think about. :2cents:

 

[It's just a six]

Re: Blown Head Gasket! w/large pics

do not port the lower portion of the exhaust port. it's that way for a reason. .

X2

 

[NecroWolf]

Re: Blown Head Gasket! w/large pics

when you did the torque to 65 ftlbs did you use the arp lube or motor oil? i remember mine saying 85 if you didn't use the arp oil. i went ahead and did 85 while using royal purple assembly lube. also did you put lube under the washer and beteween the washer and bolt head? did you follow the circular sequence during tightening?

 

[sy445]

Re: Blown Head Gasket! w/large pics

Make sure the heads are not cracked inbetween the chambers long ways from head bolt hole to head bolt hole. This is a weak spot on vortec heads. I have magnafluxed many of them with small half inch cracks stemming from the bolt holes working its way inbetween the chambers. The vortec deck surface isnt really thick. MLS gaskets are much better for thiat reason and high cylinder pressure especially from forced induction and nos

 

[0260IN3]

Re: Blown Head Gasket! w/large pics

Head gaskets don't just fail. I would look further. An ignition break up or someting like that can cause a gasket to push as well. (Just a thought) I would suggest that's not the best choice for a gasket in a performance application. I would for sure put a cometic gasket in and you'll never have to worry. I would though have the heads surfaced as anytime you push a head gasket in between the cylinders like that the surface is affected. And surface finish is VERY important with any gasket, and for sure with an MLS.

 

[Syclone #1721]

Re: Blown Head Gasket! w/large pics

I just came a cross this thread. Boy that sucks. I would definitely say check the block over very well. The surface is usually compromised when this happens. Ive seen this happen many times. The guys that were talking about timing I would have to agree with. I know that you have your A/F in a safe range but if your timing isnt correct, you will absolutely burn the gaskets here. WHat may be hapening is you may be burning the mixture right at the intake valve. This supports the timing issue. Its possible for this to happen without picking up knock because its actually very close to the correct timing events. ALso, when going to VOrtecs, you are probably going at least 5ccs smaller in the combustion chamber after they were milled. This is going to increase you compression ratio substantially. AT least half a point. I would definitely pull the other head. I mean you are 75% there. I would also definitely get them milled again. Just a light cut to make sure. Definitely go with an MLS gasket like a Cometic. I used to deal with them directly and they are a great gasket. I would also have the chambers cc'd in your head and then work out the math to get you compression back down to stock numbers by ordering a gasket at a custom thickness. Cometic will do this for you. I seriously doubt this has anything to do with the way you torqued the bolts. Just my opinion from past experience. This was very comon on small block V8 Chevys as well. ALmost always due to either timing or detonation. That is also the most vulnerable part of the gasket becasue its at its thinnest point. Hope everything works out for ya. If I can be of any help, let me know.

 

[Tooky]

Re: Blown Head Gasket! w/large pics

I used a straightedge on the block and it seems to be flat as can be, at least with my limited equipment. I could snap a photo with a bright light behind the straightedge if someone really wants to see.

Yesterday I took the head, gasket etc. to the machine shop for them to look over. They were surprised to find the head is still flat and reusable. They said it is likely because I only drove it for 5 miles after it blew. The 3 machinists agreed it was a very unusual way for the gasket to blow into the bores like that, all at once. While I waited, they milled my exhaust manifold for a nice seal when it goes back together.

Today I am going to start pulling the other head off (they strongly encouraged it).

To answer some questions:

Exhaust Porting: I meant to show the mismatch in the upper corners of the exhaust ports. I didn't think anybody would really try to port the entire manifold to match the head (you'd probably destroy the manifold)

Head Bolts: I did everything by the book 100%. Correct torque sequence, 3 sequences with loosens to burnish the threads followed by a final sequence, etc. Here's a look at the head bolts I pulled out, you can see all my sealer/moly lube:

sy445 Vortec bolt crack: Thanks for the tip, I checked but found nothing (These heads were brand new, even now they only have 700 miles on them and never even seen 195*F).

Detonation theories: The pistons look good, the plugs look good, the datalog looks good, I can't find any evidence it went lean ANYWHERE. Its still possible that something happened in the past on a run I didn't datalog I guess?? Look at Robert's melted JE piston, you would think if I was detonating, my Factory Stock pistons would have had that type of damage or worse..

Cometic Head Gaskets: Once again I am sitting on 1 pair of Victors and 1 pair of Cometics trying to decide which to use (just like last Fall). I did a Google search on cometic leaks and found dozens of threads. Even guys who had the block & head fully machined!! I paid $150 for these premium Cometic gaskets but man, thats a damn lot of work to put it together and "gamble" that it won't leak out the side of the block when I start filling it with coolant! I'm leaning towards using the Victors again and just crossing my fingers that this was a fluke. I mean, what else can I do?

 

[Christian Dionne]

Re: Blown Head Gasket! w/large pics

I put the Cometics on with copper spray and have no problems for nearly 2 years. I didn't have the block or vortecs resurfaced either. I popped the gasket between 3&5 because the wastegate rod was too tight and it went right to 25psi on pump gas. I can't remember the torque, but I wanna say I went to 75 on the ARP studs.