I've owned 3 toyota pickups. Not a single one of them have kept their seal at the manifold to downpipe connection. I tighten the hell out of those 3 nuts and within a few weeks they have somehow worked their way loose and the exhaust is noising and leaking from that spot. Happens every time to me. Some of the nuts eventually even fall off and I have a huge exhaust leak at that connection. Does this happen to anyone else? What can I possibly do to prevent this from happening? It's happened to me so many times that I would consider just welding them together is the manifold wasn't cast iron.

 

Get some of the M10x1.25 Stainless Lock nuts from Toyota .

My Toyota Parts people turned me on to them

A thin layer of Permatex #2 on the mating surfaces

Are you getting the nuts torqued even I know they can be a pain at times

Welding cast steel to mild steel might prove interesting because of the different rates of heating and cooling

Over the years I might have had leaks there prior to renewing the exhaust system once I did the exhaust no issues

Since you don`t mention what years Are you using the correct gaskets ??

 

Do you still have the header pipe held in the factory clamp where it passes the engine to bellhousing connection??

 

The stainless nuts might be an improvement, but whatever you do you shouldn't re-use the old nuts. They're split lock nuts, and lose their grip once removed and reinstalled. The new ones are dirt-cheap. (less than $2/each)

Once you get one loose nut, the gasket is no longer held snugly, and engine vibration will just crumble it. Making the joint even looser, allowing the nuts to back off even further.

Make sure you have the correct gasket, replace the nuts, and torque to 46 ft-lbs. I've never had a problem with them.

 

Nice thanks for the tips guys! I will get some of those stainless nuts from toyota. Maybe I could even do two simple spot welds on either side as well. I don't know anything about welding cast iron to steel but just a couple spot welds might do the trick. And would be easy enough to grind away for separating. No I don't still have the factory clamp that does from the downpipe to the bellhousing. It had split in half. I welded it back together and it split in half again. Anyone happen to know a part number for that little plate/clamp?

 

Doesn't look like there is a separate part number for the clamp.
http://parts.lakelandtoyota.com/show...rimLevel=18292

 

Thanks for starting this thread, this has been an issue for me as well ('86 Pickup). It looks like I need to try some new nuts and a gasket .

Daniel

 

Think these ought to do the trick?

 

Probably not. You want a lock nut. (Also, that tin plating doesn't do well in the heat.)
The stock nut (94180-40800) LOOKS like this: . Note that this one does not claim to fit a 4runner.

There are lots of exhaust lock nuts out there that don't have the split like the OEM nut does (I think they have a deformed thread, for the same purpose). But I don't know which one to get. And as I said, less that $2 each at the dealer.

 

You definitely want to fix up that exhaust clamp at the bellhousing. I got mine new from a dealer. Without it, the vibration kills the gaskets quickly. It can even cause a manifold gasket leak by loosening the studs in the head.