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TR2/3/3A tr3 exhaust manifold gasket

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sp53

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Will I reset the lifters on my tr3 and the noise is still present. It sounds like that noise you hear on an old Harley when they are idling low, kinda of pop boom. The noise is mild and most audible between 600 and 1000 RPM and after that it is gone, I think. I am thinking that it is an exhaust leak at the manifold between 2&3 but I cannot see the bottom side. There are no noticeable exhaust stains, but the little part of the gasket I can see looks gooie, like maybe fuel or heat from the engine. I guess I will have to pull it loose. I put one of those special moss intake/exhaust gaskets on about 5 years ago when I had an intake leak hoping that it would last forever just like they said. I guess my real concern is that I am constructively lazy and do not like making mistakes just to learn and I do not want to start ripping this apart when I am not sure. The lazy part is I am thinking that I can just unbolt the manifold and slip a new gasket in. My experience is that I end up taking the whole side of the engine apart, so has anyone ever put an exhaust manifold gasket on a tr3 and left the header pipe hookup and the intake still attached to the exhaust? In addition, does anyone have an ingenious way to be sure that the problem is a bad exhaust manifold gasket? Moreover can someone help me understand way a small manifold gasket leak can burn valves.

Steve
 
An exhaust leak makes a kinda breathy tick-tick-tick sound.

I've probably changed a manifold gasket as you describe but too long ago to give advice.

I didn't know that a small manifold gasket leak could burn valves so can't help there either.

Not much help am I?
 
Thanks for your not Doc and the noise is perhaps a kinda of tick tick, but I think at low idle it kinda echoes. I went out last night and drove it a little hard to see if I could get some clarity and it might have gotten louder, but sometimes when it is my vehicle my ever expanding mind can embellish the facts.
Steve
 
Aloha Steve,

Since the manifold gaskets are combination intake/exhaust (in two pieces) you will have to at least loosen the intake manifold, besides the manifolds are held tight with common clamps. Removing the carbs and intake manifold in one piece should be possible. I thinks this would give you plenty of space to back off the exhaust manifold with out unbolting it from the exhaust pipe.

With the engine and exhaust manifold cold, you might be able to slip your hand up under the exhaust manifold. Start the engine and if you have an exhaust leak in that area, you should feel the heat. If you have a helper to start and stop the engine that would make it easier.
 
On my TR3A, the studs between the intake & exhaust manifold are gone, and I've changed those gaskets (not to mention the entire head) with the exhaust manifold still hanging on the pipe. But I kind of suspect there isn't enough room to do it with the carbs still on the intake; think the carbs will hit the inner fender before the manifolds clear the studs. Just a WAG tho, so feel free to prove me wrong.

To see if you've got an exhaust leak, one trick is to carefully (slowly) pour a little ATF or motor oil into the intake. Makes the exhaust seriously smoky; so you can look for any puffs of smoke where they shouldn't be.

A small leak isn't likely to damage the valves, IMO, but it can damage the head and manifold surfaces. Those hot exhaust gases can act like a cutting torch, especially if the cylinder is running on the lean side (meaning free oxygen in the exhaust). And an exhaust leak can cause a single cylinder to run overly lean, because it 'sees' lower backpressure than the others do.
Larger leaks can push the mixture lean enough to burn valves, too. As I understand it, lean mixtures burn slower and it's possible to have the mixture still burning when the valve opens, which overheats the valve head. Perhaps that's the wrong theory, but I've seen the burned valves.

If the gasket is bad, be sure to check that the exhaust manifold isn't fouling on the side of the block. When I shaved the head for more compression, I also found I had to grind away just a bit from the bottom edge of the exhaust manifold.
Using tall nuts; fresh split lockwashers every time; and checking that the nuts were tight with every major tune-up helped too. I also added heavy flat washers on the outermost studs, between the lockwasher and exhaust manifold surface. At least the outermost nuts were brass, don't recall if the others were or not. (Found the brass nuts in the Help! section at the local FLAPS ... sold in a kit with studs for Chevy exhaust pipe/manifold flanges.) Or a good anti-seize would probably work as well (didn't know about anti-seize when I switched to the brass nuts).
 
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