Exhaust manifold gasket change

[gmcbuffalo]

Well I changed the gasket. None of the nuts would come off the studds so I gave them 4 turns and lifted the manifold off, great suggestion Dale. I found a imprefection in the surface which looked like someone tried to fix with some type of bondo material. It looked good almost like a weld. but to even out the surface I had to mill about 3/16" off the manifold. Since the stuff and nuts were more like bolts they would not tighten up with that much resurfacing. So I ended up quickly removing the "bolts" and plugging the hole hole and adding washers to take up the slack. So I lost some anti-freeze and when I started the bus from the rear started looking for leaks in my project and then it stopped from what I figured was the low coolant sensor. I fill the reservior up with water and tried to restart it. It turns over but will not fire.

Does this sensor have a reset somewhere? Could if go bad from being used? Any ideas?

If wasn't for having to mill the manifold and the no start situation this project would have been a piece of cake.

GregM

[Jon Wehrenberg]

There is no reset on the cooling sensor. Once coolant is full the code goes away.

Check your rear / front selector switch. Check the DDEC CBs, (number 19, 20, and 21 I think)

If you can try to flash your codes. That may also help.

I don't think losing coolant and then refilling it is related to the starting issue unless coolant spilled on something and made it fail, but I cannot think of anything below the manifolds that would be affected.

[dalej]

Greg,

If you take a flat washer and notch it with a hacksaw to allow it to slide onto the bolt and use it behind the main washer. You wouldn't have to remove the bolts.

Might not do you much good now though.

[gmcbuffalo]

Jon is there a flapper valve that covers the air intake like on a 8v71 that get release? How does the coolant sensor shut the engine down?

Dale I ended up doing that on the one that back by the bulkhead. If the parts dept wasn't 30 miles away I would have bought a second set of gaskets and double gasketed. I didn't use any red gasket sealer is this a mistake?

GregM

[gmcbuffalo]

I went out this morning after posting and the bus started right up. What could sitting over night have to do with anything?
GregM

[dalej]

If you are working on the exhaust manifold gasket, you wouldn't use anything but the gasket. And I'm glad you used just the one.

I get gaskets for the v6 at no charge and just cut them and notch them. The place by me has no use for them anymore. They don't have gaskets for the
v8

[Jon Wehrenberg]

Jon is there a flapper valve that covers the air intake like on a 8v71 that get release? How does the coolant sensor shut the engine down?

I don;t know if any flapper. The air enters at the sides of the body, goes through the filter (housing) to the turbo where it is compressed and into the intake manifold. I don't think the 8V intake air is intercooled.

The sensor is read by the DDEC, which controls shutdown. Make the code go away and it will not shut down the engine. You can jumper the coolant level sensor if it fails. It will not shut the engine down without the warning first.

If you think it is what shut down the engine flash the codes or get a reader on the bus.

Doubling the gaskets is a no-no.

[Joe Cannarozzi]

It was that pesky switch is what it was. Mine Tullys Wills who else.

You either have to use it frequently or do not use it at all that was my solution.

[gmcbuffalo]

Feeling good that I fix one side I checked the left for soot. sure enough small leak same spot. Took it off and found that the same casting flaw as I did on the right side but no one tried to fix it with puddy. I also so found a crack, on one of the ears going inside. So is this something that can be welded or are we looking at a new manifold?
GregM

[Jon Wehrenberg]

Greg,

The problem you will find is a design flaw. As the manifolds heat up at a substantially different rate than the heads the stresses are all over the place in multiple directions. You may be able to have it welded (a casting requires skills and special procedures) and machined flat, but the process of welding has created its own new stresses within the part.

Depending on your timing, you might want to do a junk yard search (I used to do that to get manifolds for my previous bus) and see if you can get a used one cheap. You may get lucky. Not all manifolds will have the tapped hole for the pyro however.