How to Cure a Blowing Exhaust Manifold on a 1965 Ford Mustang

As our classic cars cover a lot of miles while out on hire, it is inevitable that occasionally problems develop. They are generally fairly small ones and the key is to resolve them as soon as possible to prevent them from becoming serious problems that will either damage the car or inconvenience the customers. Last weekend our 1965 Ford Mustang GT went out for the day and came back sounding a lot noisier than normal. It is normally fairly loud having aluminum heads, stainless steel exhaust headers and a fairly noisy exhaust system, but there was definitely something wrong. I quickly traced the noise to a blow from the rear of the left hand manifold.

I popped it into the garage that we use for all our routine maintenance, to check out why this happened and he said it is a common problem with steel manifolds on aluminium heads as the bolts just work loose. If you try to do them up really tight then you run the risk of stripping the threads in the aluminium head. He tightened up the bolts which took him all of two minutes, but it was still blowing a little. He reckoned that it had burnt a hole in the exhaust gasket and hoped that the hot gases hadn't burnt the head. The gasket was duly replaced and fortunately the head was undamaged. The noise level is now back to normal but clearly there is a chance of this happening again and I don't want to take the risk of it burning the heads as this would be an expensive problem. So what to do?

A quick and easy fix occurred to me. Most trucks on UK roads now have plastic arrows fitted to their wheel nuts, pointing at each other, so that if the nuts start to unscrew then it is very obvious as the arrows have moved. OK there is no room on the manifold bolts to install an equivalent and anyway being plastic, anything similar would just melt but all I needed was something to indicate if the bolts were starting to undo. Out came a pot of bright red paint and a brush and I have painted the top flat on each bolt.

While this won't stop them undoing, a quick look at the manifolds each time I check the oil and coolant levels on the Mustang and I should be able to see if any of the bolts have moved, and tighten them up before they become loose enough to cause any damage.

Cost - zero, as I already had red paint to hand. Time to fix - about two minutes.