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Hagerty Employee

Identifying cracked heads and blown head gaskets | Hagerty Media

Today we're going to talk about the closely related subjects of cracked heads and blown head gaskets. They're not as common as what I often refer to as "The Big Seven" things likely to strand a vintage car on a road trip (ignition, fuel delivery, cooling, charging, belts, clutch hydraulics, ball joints).
Intermediate Driver

And this is why I have Hagerty extended towing coverage, some things I can do on the fly, keeping a set of tools and some parts in the car, but there have been two occasions when my cell phone was the more appropriate way to go. Knowing what's wrong and trying to fix it on the side of the road is the big problem, frustration only compounds repairs that really need a shop fix. Don't leave home without it, towing that is.

Yep, carrying the new gasket set will prevent the failure as surely as the forgotten test meter will cause an electrical fault.
Intermediate Driver

I had to let go of my beautiful little '99 Supra for this very reason. It went to a good family though with I am happy about.

I don't have the skills for that kind of repair. I guess that means I shouldn't stray too far from home with a vintage machine. 🙂
Advanced Driver

I used to, and my son does now, but I have passed from doing such things in my garage or in a parking lot. At my "advanced" age, those days are gone. I still take my vintage cars on long trips. Its part of the adventure! I have had to replace components such as a worn out generator 900 miles form home, but its been a while. Mostly it comes from doing the regular stuff to prevent the bigger stuff, which has become unheard of by younger people with newer cars. We with vintage metal have no such luxury.

Thank you Rob. Well done. In all the cars I've had, I've only overheated once, and that was in an in herited Honda EX going over Mt. St. Helena. in California. The car did not advance to a milkshake, and it is cranky at 303,000 miles and change, but overall no problems and doesn't get used much.
With your experience and advise however, I think I'll take it to my wrenches and have them to a compression check and see if we can find if there are any bodies buried anywhere.

Probably the best article I (ASE Master technician) have ever read on head gasket problems; it is on the money in every regard. Two additional comments. Welding cracked heads is not the only solution. Sometimes it is better to drill, tap and install multiple threaded plugs to repair the crack, depending on its location and nature. Obviously, this is not a DIY project, but a job for a skilled machinist. Second, I have had success on more than one occasion using classic "pellitized" Bars Leaks to temporarily seal cracked heads and head gasket leaks. While definitely not a long term solution, it's amazing what this product can do, and using it may save you an extended layover for repairs while traveling.

Boy this brings back memories. Guy junked a 1980's Subaru where I worked, I put a battery in it, turned it over and realized, "This will run". So I called the old owner asked if he minded me putting his car back on the road, he said no not at all. I put a head gasket in one side, (90 bucks) and drove that tired old car for 3 years till the seat finally fell through the floor, I had to hang on to the steering wheel to stay up and get home. Yes, I put a 2X4 across and drove it a while longer LOL.

I am in awe of Rob. He is still ready to do roadside repairs. When I was young, poor and took trips in cars from the 1960's, I made numerous repairs on the side of the road or in the parking lots of NAPA stores. Those were always stress filled days because I didn't always have enough money for both parts and gas. Now that I'm old, have a credit card, drive German cars from the 1980's and have more money, I simply call a roll back and drop the car off in my garage.

This is an excellent article. I think that I'll drive my old M20 engine just a little less aggressively after reading this.

Great info good explanation for ever step of the Torture been there done That ( more than once Old Dodge Flatheads are the easiest
Hagerty Fan
Not applicable

Watch for cylinder head bolts that go through to the water jackets. Make sure you use thread sealer.
Hagerty Fan
Not applicable

Can anyone explain why Dodge truck 3.9 V6 and 5.9 V8 cylinder heads are notorious for snapping between exhaust and intake seats? Never seen such a problem on early Chrysler 273,318 or 340 small blocks.

I have a suggestion: why don’t we sponsor a road rally or a race over a set distance where any vehicle is allowed with one caveat: before driving the course each applicant must change a head gasket first. So a modern Ferrari which can go 200 mph could compete on a level playing field with an old Chrysler capable of 70 mph.
I Imagine changing a Chrysler head gasket would take about 45 minutes, I don’t think you would even have the Ferrari air cleaner off in that time!
Advanced Driver

Does read: "the contamination of either with either prevents .."
(probably) Should read: "the contamination of either with the other prevents .."
Advanced Driver

Yup, you got me, thanks!

Great article. I have had two cars, both 3.8 NA thunderbirds blow head gaskets. Neither one had the usual tell-tale symptoms of milkshake oil or coolant. What they DID do was run normal on the temp gauge and then suddenly spike over to hot for a couple of minutes only to return to normal. A compression test on both revealed the problem. Aside from that, no symptoms. No head cracks just a wet gasket. I did not refresh either head as they were within runout tolerances, and both cars ran on trouble free for yrs. 

Community Manager

So did you only need to put the new, revised head gaskets to solve the problem? Asking since I am a 3.8L Ford owner, too. 


I just used the Felpro part number that was the stock replacement. I did take it as an opportunity to get out my grinder and open up the ports to match the gaskets. It may seem frivolous on a 3.8 Ford V6, but it did actually make a difference. That was especially true in the case of the '88.