kushiel

This one of several threads where I am trying to fix up an 87 I bought from a week a go.

It has a new block in it from the PO. We heard this noise when we bought it and were told it was the donuts where the exhaust and manifold meet.

I've search around by hand trying to feel where the leak is at but I can't find it. I poked around on the rest of the exhaust line too. It's old but looks and feels ok.

I am hoping it's not a cracked manifold.

I think the sound is coming from the front part of the 4Runner. Here is a short video with sound:



I am taking the 4Runner into a mechanic on Monday just for an inspection to see if I missed any glaring problems with it.

donomite49

stock exhaust manifolds are cast iron and known for cracking after 100k miles or so.
if you take the heat shield off you should be able to tell if its the manifold.

highonpottery

iTrader: (1)

The 2 donuts in the y-pipe do fail. Not exactly the easiest part to swap due to location, but they are pretty cheap. I recommend buying new studs/nuts if you're taking this connection apart because the stock ones are kinda one-time use design with a split nut that doesn't like to back off.

kushiel

Thanks all! I'll take the heat shield off after it cools down. Ran to the parts yard for some pieces.

I heard elsewhere on the forums that you do need neet bolts and what-not after messing with the donuts. It looks like a PitA to get at the connection. I have a driveway, some tools, and a large learning curve on how to work on these things.

thefishguy77

iTrader: (1)

Start a build thread. And post lots of pictures. It will help consolidate your questions in one thread. Easier to look back on as well. I hope your manifold is not cracked.

Terrys87

iTrader: (1)

I have had the studs that hold the Y pipe on to work themselves loose and even with new studs they wont stay in. Get new nuts from Toyota, they are terribly expensive. I have thrown away some manifolds with that problem and later was told that you could use a helicoil in them if you run into that problem. Wish I would of known of that. Just something I never thought of.

As far as getting the nuts off of the manifold and Y pipe, a long extention works great for me. When I have a good seal at the Y pipe and the manifold and problems I have had with them in the past, I wont break the seal. I cut the exhaust pipe a past the lower Y and just have an exhuast shop to weld it back up for me. Just how I go about doing it.

The manifolds do tend to crack as mentioned.

kushiel

I did take the heat shield off and didn't see any cracks on the front side of the manifold. I stuck my hands on the back of the manifold and felt around. If there is a crack there it's not very big.

I am going to go through the engine and exhaust tomorrow to check for missing bolts and other loose stuff.

thefishguy77

iTrader: (1)

Terry that's a good tip on just cutting and welding if you have a good seal.

Terrys87

iTrader: (1)

Thanks thefishguy77, the shop I use charges $15 to weld it up and is well worth the headach of a leak.

kushiel.. From my xperience, they tend to leak at the back of the head near the firewall between head and manifold. I would suggest using a Toyota exhaust gasket as well. Also I have seen alot of stripped bolts in that area as well near the fire wall. If that is the case, I have had to use a helicoil and some trucks it is easy to get to and others it isnt. If there is a stripped bolt, most likely it is going to be back there.

Might try doing the Seafoam treatment and see if that shows any leaks in that area.

Killgore Trout

i have successfully found exhaust leaks using a little seafoam, just look for smoke escaping.
if you just want it to get tightened up and plan on going with a header later,...here is what i did,
1.smack some of the iron manifold jb weld type stuff in the crack (if you find one)

2.wrestle an cuss the down pipe to manifold connection for a while then begrudgingly go to a rinky dink muffler shop,

3.tell em you want a new crush gasket (donut), have the flange snugged up and double nutted with an impact

i also had them put new rubber in all my pipe hangers, cost me 40 bucks total, the performance gains i got by sealing up exhaust leaks was well worth the cost.

kushiel

@Killgore Trout

I think I am over my cussing limit from trying to sort out the rear window electrics. I am still eyeballing that manifold connection with dread and a little hate. It looks unpleasant to wrestle with.

I did the seafoam thing a few days back but there is a new block plus a bunch of other new engine stuff. I am not sure if it would smoke or not.

highonpottery

iTrader: (1)

Your leak could also be on the y of the downpipe. I had both broken donut gaskets on the y and a crack in the seam of the y as well. Had my neighbor weld the cracked pipe and its all good now. The crack was on the inside next to tranny so could not be seen from any angle but removing it.

Terrys87

iTrader: (1)

Something I would do to mine to make it smoke is to put a few onces of tranny fluid in the plenum. That is how the old timers use to clean their motors. It will smoke!!! Neighbors may not like it.

I must of missed the rear window problem or it is in a PM. But I run a ground wire from the switch to ground. Link>> https://www.yotatech.com/forums/f199...l#post51723243 Bypasses all of the safetys.