As a few of you already know I have an 87 Bronco that I have been working on as well as a lot of other projects of lately. Well it was finally time to figure out what went wrong during the build that caused the engine to be puney as well as sound like it had a terrible exhaust leak.

I had AAA pick the Bronco up this morning and haul it out to Gary Lewis' shop. I ordered a lot of gaskets just in case there was a blown head. Gary and I attempted to do a leak down test on the cylinders. We set out to find #1 TDC with the engine still intact.

We pulled the spark plugs out and Gary covered the #1 spark plug hole with his finger to let me know when the compression stroke was coming around while I turned the motor with a breaker bar. I must have turned the motor over a dozen times waiting for Gary to say "whoa... right there". However , this never happened.

So we decided to run a compression test on #1 to see what the deal was. We hooked up the compression gauge and cranked the motor over. The gauge was jumping , but going right back to 0 instead of holding compression. We concluded that the head was leaking , but why?

Several options ran through our minds. The head could be broke and not sealing. The head could be warped. The heads were used and I didn't have them magna fluxed. I did put new springs and such in for the roller cam. The valves were all lapped and the seals were new. I did have the machinist look the heads over for cracks though. He said there were none. I also had the block decked when I had the machine work done on it. I also asked the machinist to inspect it for cracks as well. He said that he didn't see any in the block.

So now I am getting a bit nervous about the condition of the heads. So pulled the problem child head to see what was going on.

 

I would have removed the valve cover and watched while the starter turned it over.

 

Well, about that time we decided to use a straw to find TDC, knowing we'd either be right or 360˚ out. We found the top of the stroke and then put air to #1 via the leak-down tester. We had essentially 100% loss, meaning a serious problem. And, while we couldn't hear the air coming out the exhaust, surely we had it on the exhaust stroke so turned the crank 360˚. Same thing - 100% loss, but nothing coming out the exhaust, nor via the carb, nor into the cooling system, nor into the sump. On a whim I put my finger in the #2 spark plug hole and viola, there it was. But, that was not all of the air as the gauge still showed essentially 100% loss. Obviously it was time to pull the head off and figure out what was going on.

After about an hour, most of which was spent getting the !@#$%^&* header off, we got the head off. And, with the head came the head gasket. See pic #1. Anyone see a minor problem? Not only did we have a blown head gasket between #1 and #2, we had a huge hole from #2 to the outside as well as a hole from #2 to #3.

At that point Bruno cleaned the head's sealing surface and we put our home-made straightedge on it. No daylight whatsoever. A .0015" feeler gauge was held captive at each and every point. That head was, as Bruno said, "flatter than a flitter". So then Bruno cleaned the block and we tried the straightedge. No warp at all.

About that time Bruno's friend James called, the pro that's built two 9" diffs for me, two driveshafts, and one t-case. He listened and said "Pull the other head and throw the head gaskets as far as you can throw them." Which is what we did - at least the pull-the-head part. And, as you can see in picture #2, there are burn marks between all 4 cylinders on that bank. (The gasket should look like the flip-side, which is shown in #3, and have distinct circles where the metal ring of the gasket was around each cylinder.)

I'll let Bruno chime back in with the story about how he called Mr. Gasket's Tech Support when installing these gaskets. But I'll just say that if the experience with the Mr. Gasket radiator cap/thermostat wasn't enough to sour me on anything from that company, these head gaskets have done the trick. To put it in a nut shell, Mr Gasket products are JUNK.

 

The gasket set was an older one from Mr. Gasket. Their tech support claimed it was a German made head gasket from Qatar. These weren't marked front or back nor left or right. You had to be careful in order to not accidently block off the rear water passages of the block when installing them. As silly as it sounds one had to be flipped upside down from the other. They also insisted that no silver spray paint be used or copper coat.

When I called them back to let them know that I think their gasket failed Mr. Gasket offered no Mr. Warranty or even Mr. Apology for having to tear my freshly built engine apart again.

Keep in mind when I installed these head gaskets I used ARP headbolts with the torque lube and tightened them in the proper sequence as well as used the suggested order to tighten the head bolts in by skipping around to keep the pressure even. I also used the max torque ARP recommended for their product.

I am going with Fel Pro this go around . Even though they don't offer a full gasket set with performance head gaskets (0.039" compressed thickness) or even a head set with the performance head gaskets in them and it cost me a fortune (head gaskets alone are $40 each and I still had to buy a head set for the exhaust and intake gaskets too)

Gary suggested to be sure that I get the heads magna fluxed. I agreed because this engine only has 500 miles on it and already the top end has come back off and I sure as heck don't want to go through this again.

Another thing we were kicking around is to use some copper coat on the next install regardless of what tech support says. I wanted to check the deck height to see how close to quench I ended with. The deck height appeared to be 0.008". That is if we got the piston all the way up. So it could even be a little less. I was happy because I was trying to get to below 0.050' and it should put me around 0.046"-0.047".

 

Go with the Fel-Pro gaskets every time. We use them at the service garage on everthing we do, never been let down. Yeah expensive, but it's a PITA re-doing something because of some crappy gasket.

 

expensive gaskets cost far less than the labor of doing it twice!!

 

Does anybody know if the valves have to be disassembled to have the heads magna fluxed?

 

You found the problem!
Why do you not trust your machinist?
Don't you use him because you respect his experience?

I'd trust Fel-Pro, Victor/Reinz, Cometic.

As I pointed out to Gary with his rad cap, Prestolite (Accel, Mallory, Mr. Gasket, et al,) are NOT to be trusted anymore.
It's a profit driven corporation taken over by beancounters sourcing the cheapest crap they can sell.

 

I can only inagine what you would have in it if you were paying someone to fix it. No more Mr.Gasket for me.

 

I think you got lucky by finding that with no other damage. This could have happened if let go longer.

Head:



Block:



I've also heard of the Victor gaskets doing this. I've never had a Fel-Pro gasket fail on me before.

 

Jim , I use a couple of reputable machinists. However, I didn't have the heads checked for flatness or magnafluxed. Then again I couldn't believe just how flat everything really was. I know there is a tolerance for V8's around 0.008"-0.010" for headgaskets, but there isn't more than 0.002"-0.003" between the block and heads. So I am pretty confident that the gasket was just a POS.

Jim,how close to optimum quench do you think I am getting at 0.046"?

 

I think that's really good.
I wouldn't go less than 0.040"

 

Note to Bruno, the drivers side head has 2 verticle hash marks at the rear exhaust port just below the casting seam.

 

How the heck can you see that from those photos Gary?

 

Jim - That was Bruno in my shop using my computer to make a note to himself.

Bruno - Let's check some things before we go back together. First, let's calculate the compression ratio. What is the combustion chamber size on the heads? What is the dish in the piston? What's the bore?

And, what if the heads aren't as thick as the stock heads and your ARP bolts are bottoming on their threads? Please measure the thickness of the heads as closely as you can at the bolt holes and I'll check the bolts.