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MG TD TF 1500 - To seal or not to seal that is the question.

First the thermostats. Do these two surfaces need any special preparation and/or do the gaskets need any type of sealant?
What about the water pump housing surface? Does the paint have to come off?
Sorry for the sideways picture but I'm not in control of my iPhone.

Mort 50 TD

Next question is the exhaust manifold gasket surface. Do I need to remove this paint?
The machine shop was a little bit over zealous with the paint.

Mort 50 TD

Mort,
Well, the machine shop could certainly teach their help to mask mating surfaces. I am not certain that paint will be a problem on the thermostat housing, or for that matter on the exhaust manifold gasket area. That said I have never seen such painted surfaces assembled. Why take a chance? We know that bare surfaces work for years. Good luck!

Jim Haskins 1953 TD
J M Haskins

Any sealants required on these three gasket services?
Mort 50 TD

Mort,
Hot antifreeze will lift the paint on the inside of the thermostat housing. It will flake off and get stuck in the radiator.
I would definitely remove it there.

I believe the exhaust manifold gasket only makes contact at a line/ring point. That leaves the paint inside the ring exposed to hot gasses. It will eventually burn away and could result in an exhaust leak.

On the water outlet gaskets I would use permatex.

I know of no High temperature sealant. There may well be one now that I am unaware of. I think the exhaust gasket, on two clean surfaces should do the job.

Jim B.
JA Benjamin

Mort,

I highly recommend Permatex Ultra Copper High Temp RTV on your exhaust manifold.
http://www.oreillyauto.com/site/c/detail/PERS/81878/N2362.oap?ck=Search_N2362_-1_-1&pt=N2362&ppt=C1984

Gene
Gene Gillam

Positvely remove all paint on mating surfaces. I suggest using a good straight edge on the thermostat and housing to make sure straight. They often distort over time, leaving a gap in the middle. Or you can dry fit and use a feeler gauge or something. If original rough cast iron surfaces, use Permatex aviation sealant, or a very, very thin wipe of the blue stuff. George
George Butz

I tend to use Hylomar on all seals except intake/exhaust and sump. On sumps I use Permatex hardening and on intake / exhaust I fit them dry as they often have to shift a bit due to the different expansion rates of iron and alloy.
Kevin McLemore

Remove all paint on mating surfaces. No sealant on exhaust ports, bare metal. Thin coat of Permatex ultra copper or quality sealant on thermostat gaskets. PJ
Paul161

I'm with Kevin on the hylomar. Razor blade off paint and coat the gasket. I used to use the special blue "gorilla snot" for the water pump, but lately have been using hylomar for that, too. Permatex makes a hylomar duplicate that is quite good, "Permashield fuel resistant gasket dressing and sealant #85420. Ebay always has it if you can't find locally. No other advice on exhaust manifold gasket dressing.
D mckellar

All surfaces now clean and ready. Latex gloves, a rag around the finger and a bit of xylene. Carefully applied the paint comes right off. Very simple and no scraping.You must use caution so you do not remove paint that isn't the proper location.
Thank you all for your advice and help.
Mort

Mort 50 TD

Well done, Mort. But then, what else would we expect from you? Bud
Bud Krueger

Have the intake & exhaust ports been enlarged? I cannot tell from the photo.
The valves in the combustion chamber should also be in shrouded, the combustion chamber should be machined out to the gasket area.
Len Fanelli

Still recommend Ultra Copper on exhaust/intake gasket. Use it on my extractor manifold with supercharger...no leaks.

Gene
Gene Gillam

Thank you Bud.

Len, I only race the trucks on the turnpike not really fast cars. The reports off fairly clean but not machined all the way. I'm happy with the results.

Gene, I have a tube on hand ready to go.

Thank you all
Mort 50 TD

My rules of thumb:
Inside thermostat housing: No paint
Manifold gasket surface: No paint
Water pump mating surfaces: Paint OK on block side
Thermostat housing mating flange: Paint OK

Use sealer on all cooling system mating surfaces to account for uneven surfaces. If machined flat, no sealer should be necessary but they are rarely that flat.
Steve Simmons

This thread was discussed between 05/06/2016 and 11/06/2016

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