found HEAD GASKET LEAK...need advice...

hotrodder68 · 10-27-2009, 03:20 PM

Well if anyone read my threads in the past 3-4 months I was having heating problems on the highway. In hot weather I was seeing 230' at 55mph (3000 rpms). I ran a compression test, put on new water pump, highflow thermostat, no coolant in oil, no oil in coolant, no smoke from tailpipes, etc...
My cooling system is this: Stewart high flow 180 thermostat, Aluminum GMB water pump (yes it rotates the right way), 2 row high flow aluminum radiator, new Gates hoses that do not collapse, 2500cfm flex a lite electric fan. This system cooled the car beautifully for the first 10,000 miles of the engines life. Then it started running hot.

Anyways I will save you from too much detail. My dad and I were at the end of our rope trying to figure it out. I finally took it to a trusted mechanic and he ran a test using dye and it apperantly showed him that it is a head gasket. I would rather save the oodles of money and fix this ourselves so I will pick the car up tommorow.

So, what head gasket should I use to put the GT40 heads back on to my 68 block. I was thinking something thin to get me closer to 10:1 compression. I am at 9:7:3 right now. Any suggestions based on good experience? Thanks guys and gals!

428Rcode · 10-27-2009, 03:24 PM

FelPro PN 9333PT1.

Don't waste your money on anything else.

66 6 · 10-27-2009, 03:25 PM

+1
and no gasket it going to get you to 10.0

I'll also like to hear more about the dye trick. Where was the dye showing up?

428Rcode · 10-27-2009, 04:49 PM

Quote:

I'll also like to hear more about the dye trick. Where was the dye showing up?

It's not a trick. It's a diagnostic tool. A little pricey, but if you're unsure of a blown head gasket it's a money/time saver.

A solution (dye) is added to your coolant. The engine is run for a few minutes to circulate the solution throughout the engines coolant passageways. The "tester" extracts a sample of the coolant and tests it. I've forgotten the exact means, but the tester determines if the head gasket is blown.

It's similar to the old "anti-freeze percentage" tool that can tell you what percentage of your coolant mixture is anti-freeze, but a little more high-tech.

I think the kit is around $40.

tburch · 10-27-2009, 05:43 PM

Could this not also be a cracked block or cracked head?

bigb427 · 10-27-2009, 07:37 PM

If a solution was added to the cooling system it was a dye to be used with a UV light to check for external leakage.

What you described sounds like a tool designed to take a sample of the gases coming from the cooling system. The fluid in the tester will react with hydrocarbons (combustion chamber gases) and change color.

If no hydrocarbons are present the test fluid will not change color and the car is ok at that point.

hotrodder68 · 10-27-2009, 10:14 PM

Yes, that sounds like what he described to me as far as the dye turning color based on some chemical reaction. Pretty cool.

He also said it could be a cracked head but I wonder what would have cause an iron head crack. They were full inspected and all components replaced in these GT40 iron heads to the tune of $500 before I installed them.

Anyways, I am not looking forward to the process of tearing it apart but I am happy to finally have an answer on this problem after months...

Thanks alot for the recommendation on that gasket.

-Nick

JohnnyK · 10-27-2009, 10:20 PM

Tearing it apart? It's a couple hour job, especially if you're carbed. I had to do it twice, one after another, after a wrench broke off and went down the plug hole on my car. I'm sure a search will turn it up.

Of course, I think we're all anal and clean our bolt threads to perfection, etc, so the hours stretch onwards.

Teebone · 10-28-2009, 05:18 AM

I would take off both heads and have them milled slightly to make sure they are true and not warped, then I would use good old trusted Felpro gaskets. The milling will also get your compression closer to the 10:1 you are looking for.

gotstang · 10-28-2009, 08:32 AM

I'd get the heads milled like Vinnie suggested and use an .039" gasket. Get those things down to 55-56cc and 10:1 is no sweat.

hotrodder68 · 10-28-2009, 06:33 PM

Believe it or not they have been milled down so much that they measured 53cc before I put them on. I am not sure how much more they can be cut. Originally Iron gt40 heads are 62cc or so. Maybe they will need to be milled more though after overheating...

whisperer · 10-29-2009, 02:36 AM

Quote:

Originally Posted by hotrodder68

Believe it or not they have been milled down so much that they measured 53cc before I put them on. I am not sure how much more they can be cut. Originally Iron gt40 heads are 62cc or so. Maybe they will need to be milled more though after overheating...

You are describing these heads as GT-40's so I'm assuming that is what they are, not P's right? If they are OEM GT-40's then they have already been cut WAY too far to get 53cc out of them. The stock deck won't handle that and will crack, likely the overheating problem. GT-40's will take about 57-58cc's and live without power adders. Since the engine has been running really hot a few times I would expect that the heads may have cracked.
There are a bunch of SBF iron heads out there on the aftermarket that are very affordable. If you are being cost-concious then look at something like the WP Windsor JR. They can be cut to 53-54cc and maybe more.

jeff33702 · 10-29-2009, 08:29 AM

Sometimes a normal compression test will not show a problem. I would suggest a leak-down test. I know that you already determined that you have a head gasket or cracked head problem but it would help you find it if you could determine what cylinder it is on before you pull it apart. I've pulled heads off a car before chasing a head gasket and couldn't see where the problem was. I was sweating it putting it back together because I didn't actally "find" a problem.

hotrodder68 · 10-29-2009, 08:30 AM

Yes they are the non p heads. I thought taking 10cc off of them was alot. I guess we will find out soon. I think however, that if they are cracked I will be looking into something like used twisted wedge heads or something else. I already have about $700 into these heads and I could have had some more modern design aluminum heads.

I'll keep everyone posted as I plan to take it apart Sunday. Thanks!

OH and I also have a trans leak at the linkage on the side of the trans and the speedo gear...Ugh does it ever end? This c4 was rebuild 2 years ago. I think they are just meant to leak. Not to mention my new water pump leaking...

gotstang · 10-29-2009, 08:45 AM

Good crap, that means they milled off .070" and something like .040" is usually the recommended limit.

Don't bet the farm on my SWAG, but I wonder if you have enough deck left to seal the headgaskets? OEM Ford heads don't seem to have the thickest decks in the world and it seems like they milled the snot out of them,