Hi all.

I just got myself a 77 Hilux. It looks like a Mad MAx nightmare, but it runs like a champ. There is a pretty massive exhaust leak at the manifold though.

so this is the back of the manifold.



There are supposed to be Bolts there, correct? I know that is a stupid question, but after looking at it for a minute and wondering why there aren't I got in my own head and decided to ask a dumb question before I went and picked up some to throw in there. It should be noted, however, that there is exhaust shooting out of the bottom hole.

Also, anyone know what the tube to the right is? Its been hacked off of something. Should I just cap it and forget about it?

 

Interesting "solutions"...

Yeah, there should be 2 bolts there. Actually, there should be 2 studs and nuts. 20R exhaust manifolds have a total of 7 studs/nuts (bolts) holding it onto the engine.

The tube on the right looks like the air injection manifold. Rather than cut it, the PO should have just unbolted it.

Oh, and that bolt sticking up from the manifold is plugging the air injection port to which the air injection manifold was bolted. PO could have just left the air injection manifold alone since, if you trace it back to the air pump, there is a one-way valve in the tube.

*edit*: Oh, now I see why that bolt is stuck in there. Looks like the two bolts that hold down the air injection manifold broke inside their holes.

Again, the PO had some very interesting "solutions"...

 

Yeah, he was an interesting dude.

So.. Should I just try to source some bolts that fit and throw them in there?

As far as that bolt goes, I'm assuming that for the time being that will be okay. I'm going to get a new manifold down the road so I probably won't written too much about it for now unless it's going to cause a problem.

 

Yes, you should find some bolts and bolt the manifold correctly. As the gasket erodes (you will need a new exhaust manifold gasket as well), it creates a giant air leak. Perhaps this is an old mechanic's tale but having that cold air hit the exhaust valves might warp them. That's what I was told, anyways.

Also, driving around with the manifold torqued down unevenly may cause it to warp and then it will never seal correctly.

And buy more than just 2 bolts; get half dozen or so. In my experience (79 Celica w/ 20R) the manifold bolts like to vibrate out once they are disturbed unless you torque them just right and you're probably going to lose a few more.

 

Great. Thanks for all the help.

 

The 20R exhaust manifolds were known for cracking between the #2 and #3 cylinders. Something to do with the factory heat shields. I had the two bolts your missing also fall off (vibration?).
Your thread pitch is 10 x 1.25 mm. Chase the holes with a good quality tap. You can buy bolts at most hardware stores or you can order stud sets from any autoparts store.

 

Do it right and you shouldn't have a problem again
Get studs and nuts, and loctite the studs in there. Less chance of stripping with studs too.

 

LCE has a fairly economical set of head studs. You can also get them OEM through a dealer. The price is a bit steep for what they are but they are good quality.

If the gasket surfaces are pitted or warped or in any way suspect I recommend RemFlex gaskets. Tough to find locally, and a bit pricey, but fantastic stuff.