Welded intake back on, still have problems... (1 Viewer)

[Jesper]

The intake manifold on my 83 FJ60 cracked on one of the mounting ears/flanges. The crack ran through one of the intake ports and was visible from the outside as well as inside once I took everything apart.

I had been having some choppy idle issues and was making about 15-16" of vacuum at 4000' elevation, should be doing a touch better than that. Did the carb cleaner spray test and found the crack / leak. initially tried to patch it with JB Weld with no success.

I tore it down had the manifold welded, refaced and put back on with a new Felpro gasket set. The weld was ugly and only attended to the exterior, the crack is still visible on the inside of the plenum/runner but since I'm always pressed for time I crossed my fingers and hoped for the best.

After reinstall I'm still running horribly rough and making 15" of vacuum and get an RPM bump when I spray the cracked area with carb cleaner. I'm going to tear it down again, get opinions from a different machine shop as to whether this is even repairable and maybe try with a Remflex next go round.

In the meantime, if anyone has a spare intake (cast# 17111-61021) they'd be willing to part with please let me know. I'm due to move states again in about 5 weeks and of course this is creating another crunch.

Thanks all.

 

[Spike Strip]

I think at 4000', 15" of vac is low-ish, but normal. Is the gauge needle low and steady? Have you done a valve adj lately?

Next install, use some coppercoat on the gasket. The stuff in the can, not the spray.

Why didn't the shop just weld the entire crack and clean up the weld inside the runner? (and maybe find someone who is better at welding aluminum)...

I understand your crush on time, but crossing your fingers fingers and hoping for the best now means you have to do it again.

 

[Output Shaft]

60 Series, Intake/Exhaust Manifold

Although you've verified with carb spray that indeed there still is a leak at that crack repair, 4000 ft is an awkward elevation for a 2F with the HAC valve. Either it's open or closed but either way isn't ideal at that elevation.

 

[Jesper]

I wouldn't be too fixated on the vacuum measurement by itself as it's not that far from what I would expect, but I was making about 18" not too long ago so I know somethings up. That and the rough running. I'm not sure why it was welded that way - I don't know anything about welding, maybe they couldn't adequately get inside the runner (?)..but I will be getting a second opinion. And I do have the copper brush-on gasket sealer but had a weird feeling I would be doing this over and didn't want to create additional ass pain/scraping/cleanup.

With that said, any recommendations on where to apply the copper coat ie; both sides of gasket or only on the intake side/block side?

OS I appreciate the link but $450 is way out of bounds for me at the moment...really hoping to come to a more reasonable resolution.

 

[Spike Strip]

Some just use it around the exhaust ports, both sides of gasket. I've used it both sides, entire gasket, and it worked fine. You can't go wrong using it, and worse thing that happens is a PITA clean up next time it's removed ... But if the combo is true and sound, I'd just leave the gasket dry or only around exh ports. That's what I've seen some LC pros do.

Post in the wanted and look in the parting/For Sale in Classifieds. Should be able to find a good one for under a $100.

Use the half-washers with the new one to avoid the same crack! Or have the machine shop spot-face the attachment surfaces.

 

[brody]

Usually when welding a crack like that, the crack has to be ground out enough to get multiple passes from the inside out. Thats how I used to perform such tasks. If the crack is not ground out, the weld will have impurities in it from the carbon build up in the crack. All alloy welds have got to be clean!!! Like scrubbing the surfaces with a clean wire brush and acid. Just my hillbilly advice when you consult a welder to perform such tasks.

 

[Jesper]

Will do, Spike & Brody. Thanks for the info.

I do have some follow up questions (may make another thread);

1.) My understanding is the intake/exhaust can be separated but the unit should be reassembled and machined as a unit to ensure it is flat. The machinist here was adamant that it shouldn't be done that way. He said the exhaust manifold was flat so he left it alone. He refaced the intake after the weld repair. His instructions were for me to keep the two halves somewhat loose, snug the manifold to the block with no gasket and then tighten the intake / exhaust against each other. Logic being the block would naturally pull the two halves into plane and then tightening them down together would "locate" the intake/exhaust against each other. Afterwards remove, install gasket and replace the manifold and torque to spec. Can't say I've heard of that before. I did pass on my understanding of the 2F manifold based on the multitude of info here but at the end of the day I figured this guy has been doing this much longer than me. I tried it his way and I don't know if the resultant leaks were inevitable because of the bad weld or if the entire planing and re-install was flawed from the get go.

2.) Carb question- While trouble shooting and trying to locate any other leaks or issues I verified my vacuum lines were routed correctly. I'm desmogged with HAC retained. My primary (inner) distributor advance is piped direct to the advancer port at the base of the carb. The secondary (outer) advance is hooked to the HAC as well as gas filter via a tee fitting. I noticed that while at idle if I pull the hose off the secondary advance my timing/rpm noticeably slows. If I remove the hose off my primary advance there is no noticeable difference in idle speed or "tone", seems to have no effect. Is that normal? I understand the primary advance is load-driven based on operating conditions so I imagine at idle it may be pulling any, and the HAC may be constantly activated based on elevation. Just want to verify this sounds normal...thoughts and input solicited.

Thanks!

 

[brian]

the typical aluminum nightmare...be it an intake or a john boat.....why is it people think putting jb weld on it, is a good idea and then expect somebody to weld it when the epoxy doesn't work?
you didn't do that welder any favors, and now want to call it a bad weld.

and if you machine the manifolds separately one will be thinner, or thicker than the other depending which one you're looking at. since the share studs and washers/nuts they NEED to be the same thickness.

 

[Jesper]

Point taken.

As to the units needing to be the same thickness, I understand that and passed that on. The machinist stated he spot faced a couple of the bolt holes to make them all sit evenly. I'm curious about the process of leaving the two halves loose, bolting them to the block and then tightening them down. It makes sense to me as I visualize it, but haven't heard of anyone doing it that way.

Thanks

 

[brody]

Jesper, I left the two halves loose when I recently changed the manifold gasket. I found it to be a bit easier to get the proper fit. I didn't have a flat surface to mate the two together on. I fit it loose and snugged up the manifold flanges first and then snugged and torqued the mating bolts, then torqued the flange bolts like normal. It worked first try for me, but as always, your mileage may vary. I hope thats what you were referring to...if not, my apologies.

 

[Jesper]

It was, and thanks much for the response.