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440brew
10-14-2011, 10:44 PM
Where is a good place to buy replacemnet exhaust manifolds for and 89 351?

I Found out today mine are very rusty and flaking. Can you just use POR 15 or some product like this to recoat the inside?

thatsmrmastercraft
10-14-2011, 10:53 PM
Discount Inboard Marine is a great source.

http://www.skidim.com/

Willski
10-14-2011, 11:10 PM
I bought my '84 replacements at http://www.marineexhaustmanifolds.com/

Good to deal with.

Skidim has also been good to deal with too. Didn't compare the prices though.

Engine Nut
10-15-2011, 06:06 PM
Check inboardonline.com The P/n for the cast iron manifold for a 5.7l is 531051 and price is less than skidim or marineexhaustmanifolds.com. The manifold for a 351 is p/n FM-1-83 and it is a better deal as well

east tx skier
10-15-2011, 09:12 PM
Rusty and flaking is par for the course. It will be years before they are unusable. How bad are we talking here?

CantRepeat
10-15-2011, 10:40 PM
Rusty and flaking is par for the course. It will be years before they are unusable. How bad are we talking here?

x2 on eastie's post.

All of them seem to surface rust right around the exhaust port.

440brew
10-16-2011, 12:17 PM
Rusty and flaking is par for the course. It will be years before they are unusable. How bad are we talking here?

at the rear plug you can feel it loose and flakey there. Not much but enough to pull out with one finger. Maybe I should just pull them off and give it a really good flush first.

joniron1
10-17-2011, 06:39 PM
I was convinced mine were shot .My buddy said take them off and sand blast them you may be surprised at how thick of a layer of rust will form from a thin layer of base metal.He was totally correct after blasting them they looked like new.I painted them with por15 exhaust manifold paint then a coat of por15 engine paint it has held up real well this summer. It cost ~$100 for new bolts ,fittings,gaskets and paint.Im sure glad I looked at them before I ordered new ones like I was about to do,I think it was going to be ~$450 for a new set.

JLMax16
05-01-2013, 09:05 PM
Speaking of rusty and flaky.... is this bad? Should I replace my exhaust manifold? It's getting hot enough to melt the carpet (you can see the half moon shape in the bottom of the picture).

mikeg205
05-01-2013, 09:14 PM
Speaking of rusty and flaky.... is this bad? Should I replace my exhaust manifold? It's getting hot enough to melt the carpet (you can see the half moon shape in the bottom of the picture).

Yes ! - probably not getting good circulation there.

AZDave
05-01-2013, 09:33 PM
I would not wait. Mason marine in California sells GLM manifolds, or go straight through GLM. Cheaper than Ski Dim

JLMax16
05-05-2013, 07:37 PM
I've read bad things about GLM, have they improved over the past few years? The issues I read were people having to get them machined because they weren't flat.

JLMax16
05-05-2013, 07:42 PM
And would anyone know the part number for the LTR 330?