FJ40 Exhaust Manifold Crack (1 Viewer)

[75PIG]

1972 FJ40 -- F Engine

Heard a "whistle" at idle and when decelerating. Figured it was the intake/exhaust manifold gasket - took it apart... it was shot. Then, separated the intake/exhaust - that was a bugger of a job... have a new gasket for here too. I then sandblasted the exhaust manifold. Cleaned up real nice but the thermo rod is still frozen - at about half mast - I guess I can live with that.

Found a crack 1.5" long (hairline but through-and-through)-- can it be fixed? Heard you can not successfullly weld cast. A friend said to try to grind a groove and fill with JB Weld and grind it down. The crack starts at a corner beneath the intake manifold and migrates towards the #3 cylinder.

Is this a hopeless salvage attempt? It only has a minor warpage "up" towards the #6 cylinder.

If so, does anybody have a used stock exhaust manifold laying around that they replaced with a header -- my intake is in good shape and I want to try to maintain the stock appearance on the FJ40 "F" engine plus I have a newer exhaust system.

 

[dbenke]

You can braize cast with a bronze rod, but I would opt for a header. I'm sure you can adapt the exhaust to it. If you are a member of a local club, ask on the message board, I'm sure you can find one (cheap)

 

[75PIG]

Thanks for the Braize tip.... might try it versus JB Weld.

No local club but most of the local guys have converted to V8s long ago. I am a hold out but got to admit that "parts" are much more available on the Chevys.

 

[Fast Eddy]

You can fix the manifold with this Permatex 1000 degree epoxy putty:

http://www.permatex.com/documents/tds/Automotive/80334.pdf

PERMATEX® 1000° PLUS Exhaust Repair Kit - Google Search

Put it on both sides and get as much as you can into the crack.

YMMV. Don't expect it to last forever and if it does you can be pleasantly surprised.

Then machine the manifold flat before you put it back together. I did mine with a large flat file and some time. A belt sander table would be easier. Some machine shops will do it for you, some won't.

 

[75PIG]

Must be better than JB Weld --- will check into a local machine shop to see if they will fix. Both sides will be tough --- tough to get inside to place the material.

Thanks

 

[Pin_Head]

I don't think that I would even worry about a 1.5 inch hairline crack. If you can't hear it make a ticking noise when it is pedal to the metal going up hill, then it isn't leaking much. If it bothers you, braze it up. Brazing is a permanent fix.

 

[75PIG]

Thanks Pin_Head

 

[65swb45]

I agree with Pinhead ...except that I would take the opportunity to surface the manifold while it is off. This should minimize the stresses that caused the crack, and increase its remaining lifespan. Cheap insurance.

Best

Mark A.

 

[malcb]

I am waiting for some HTS-2000 Al brazing rods to arrive from these people. For the price I thought they might be worth a go, I am attaching some injector fittings onto a 2F manifold so no massive strength required and hopefully minimal distortion which was the concern with TIG.

Aluminum welding - Aluminum Repair - Aluminum Brazing - AluminumRepair.com

Notice they also do ones for cast iron.

Anyone ever used them? They seem to have been around a while and mostly favourable comments on the web but not many proper reviews.

 

[75PIG]

Mark

Yes I was going to surface the complete unit, intake and exhaust, after I get it back together. I would post a picture but we had a recent house fire which smoked up everything and put us out of the house for a couple of months .... put a damper on restoration. Got many other things to get done now.

It was a clothes dryer fire.... not a cruiser fire. Lucky my wife was home or the garage with the 72 FJ40 and 75 FJ55 would have gone up along with all of the other flammables in the garage. That would have been a tragedy. All-in-all, no one was hurt and just smoke damage --

The fire chief waded through the garage and saw the FJ40 taken apart with all the nuts and bolts all laid out nicely --- he needed to get the the circuit breaker main in a "smoke filled" garage. He was thinking to himself.... he did not want to screw up my project and that was one of his priorities (nice guy). The rest of the fire department came up to me and said that they could get the cruiser's out of the garage for me.... they could hang onto them for a while at the firehouse.

Well, so much for the huse fire saga... I still have to get this done and get it running again.

Thanks for all of the advice.

Jim

 

[Kelly FJ55]

Hi 75PIG,

I have a 69FJ55, put a new header on it about a year ago, cost $250 TPI 615-826-8853, they said it might require some modifications to fit, but with my F engine, and OEM 3 speed linkage, it fit right in no mods.

I had to have the collector welded to my exhaust pipe, but that was it.

Actually, my pipe was in kinda rough shape, so I had a whole new pipe installed and routed out behind the pass side tire. But if your pipe is good, it is a pretty simple weld job for a muffler shop.

I would suggest you try to get a copper collector gasket, as mine burned out pretty quickly, it was a paper/cardboard type gasket, but after I put in the new one, no more leaks.

I have been unable to find a copper block to header gasket, but if you can find one, I would rec commend that. If you find one, PM me with the info, I would like to have one for back up. Thanks and good luck on your repairs.

KellyFJ55

 

[malcb]

snip

I would suggest you try to get a copper collector gasket, as mine burned out pretty quickly, it was a paper/cardboard type gasket, but after I put in the new one, no more leaks.

I have been unable to find a copper block to header gasket, but if you can find one, I would rec commend that. If you find one, PM me with the info, I would like to have one for back up. Thanks and good luck on your repairs.

KellyFJ55

Interesting - only come across copper head gaskets, have you used a copper manifold gasket, if so what sort of thickness do they come in?

 

[poose]

I have an exaust manifold from a 2f in the garage if it will work you can have it

 

[Downey]

I'm not sure I would agree with the wisdom of repairing and resurfacing the stock manifold, kinda a question of cost of doing so versus longevity after doing so. To me the big issue would be what if my repair job lets go when I'm a zillion miles from home and knowwhere near additional repair. If you opt for repair & resurface, you could spent as much as you'd a spent for a Header, but not get the gains the Header provides.

 

[brian]

I am waiting for some HTS-2000 Al brazing rods to arrive from these people. For the price I thought they might be worth a go, I am attaching some injector fittings onto a 2F manifold so no massive strength required and hopefully minimal distortion which was the concern with TIG.

Aluminum welding - Aluminum Repair - Aluminum Brazing - AluminumRepair.com

Notice they also do ones for cast iron.

Anyone ever used them? They seem to have been around a while and mostly favourable comments on the web but not many proper reviews.

you'll put more heat into it with the brazing, then you would have if you just straight welded it.
alum does'nt move much when welded.

 

[malcb]

you'll put more heat into it with the brazing, then you would have if you just straight welded it.
alum does'nt move much when welded.

Your not wrong with that, seems to have worked OK but it would have been easier to take it down the road an get it tig welded.

Still next time I hope I will have some 3FE parts and I won't need to adapt a manifold.

 

[jimhendrixx]

Yeah, i am in the same boat and am opting for a header. Got the two piece three into one set up.

 

[75PIG]

The house fire has kept me from being able to get back onto the site and not allowed me to work on the cruiser. Thanks for all the advice on the headers --- I have been trying to keep it "stock." Will probably have to convert someday --- maybe soon.

Poose --- I have a 72 "F" engine --- not sure a 2F exhaust will fit. Maybe it will. I will research it a little more.

Thanks again

 

[motoloco]

Why would you even try to fix the stock one? Good stock ehxaust mans are a dime a dozen, I have a stocker if you need it.

 

[71-CRUISER]

I would repair the stock manifold long before I would ever install an aftermarket header of any type. Most headers will stay sealed for about 6 mounths and some less depending on what gasket you use and who instals it.
If the stock manifold is salvagable than fix it and if not find a good used one and claan that one. You will have to have them resurfaced but it will stay sealed for another 100,000 miles if you do it correctly and no header will do that. Plus it is the way Toyota intended it.

This one is from a 73 that we are pulling a header and Webber setup off of so that we can install a stock manifold, carb and air box. The heat deflector was rotten like most so I just remove them and plug the holes w/ some 8mm bolts and some Ultra Copper RTV. It would be shinier but I ran out of high temp black paint.