351W Block Question
 

1993 F250 351W. Stock exhaust.
Hello to the list.
I can't seem to describe this correctly so starting a new thread. When looking for the chronic right side exhaust leak the muffler shop said I was missing a bolt. The photo (not my motor) shows the 'hole' I think he was talking about and it looks to be threaded. I dropped the fender well liner to see and it looks like 'something' is missing. Motor runs fine except for the exhaust leak. Any one have a clue as to what should go there? The local Ford dealer didn't and I can't find anything on the net.
Thanks, Steve

What's on the other side?

There's a thermactor (smog pump) tube that runs across the back of the engine from head to head. It tends to rust out, so it may be missing.

See 9B449 at left in pic. This is 1988/89, but 1990/96 will be similar.


https://cimg1.ibsrv.net/gimg/www.for...ed51a62dee.jpg

Thanks for the quick reply. The crossover tube from head to head is intact although hard to see it's condition. This hole(?) is on the block but it's raining so I can't see yet what's on the other side. However I have come across a couple of rear views and that 'hole' might just have a plug in it but can't really tell. Whatever was there is definitely missing.

Great, thanks for the photo. Looks like the same hole so you're saying there is nothing in your's? It's a dummy hole dead end?

That may be a knock sensor hole but it could also be for mounting the clutch bracket or something, in either case it's a blind hole and it's in the block so it has absolutely nothing at all to do with the exhaust so it's not your problem... you could have a cracked exhaust manifold or a leak in the thermactor(air injection) system.

Here is a pic of the rear of a 1/2 ton 5.8 motor and the crossover tube, this assembly should be rigid and a good test is to reach in over the motor and grab the hose and give it a good shake. It should not move, if you break it it was rusted out anyway. Chances are this is the source of your exhaust leak.

https://cimg2.ibsrv.net/gimg/www.for...4100138466.jpg

Thanks again Roy for your info. Since the weather cleared it inspired me to poke around with a long welding rod and it is indeed a blind hole. Should have done that first. Going to have a chat with my muffler guy. I will respond to conanski and rap this thread up.
Steve

Thanks for the input Paul. As I replied to schoo it is a blind hole so I will forget about it. I didn't think it was part of my exhaust issue but was led to believe that a bolt was missing or broken and haven't found any others (yet). Just wanted to replace something if needed. I have assumed that the ex. manifold was the problem for a while now but will give the crossover tube the grab test when I can. If that is the source of my exhaust leak then I will gladly take it as opposed to a bad exhaust manifold. I'm new here and sure to have other issues but we can put this thread to bed.
Thanks again everyone,
Steve

My 96 5.8L has a nasty exhaust leak on the right side. It was bad enough I thought I had a cracked manifold. But it was the EGR supply pipe rusted thru. So don't over look that when you've got a exhaust leak. That's at the front of the right manifold on mine. But I don't know if that's the location where yours is leaking. But make sure to check that out. You can get a new one if your is bad too.

Thanks for your thoughts on this. I have heard about the EGR tube so I planned on checking it when weather cleared. Was going to do the 'grab test' on the head to head crossover tube but can't reach it from the top. So I took it to another muffler shop and he didn't mention any broken or missing bolts but said the back two exhaust ports have soot around them so that must be it. Oddly he said the gasket is leaking but my understanding was that they didn't use exhaust gaskets. Looking like a bad manifold, crap.

Yeah no gasket used normally but the manifold mating surface must be perfectly flat. You could have a couple broken bolts on that manifold, they will corrode so bad the heads remain stuck in the manifold.

It's pretty common for a gasket to be installed when engine work is done. That's just easier/cheaper then having everything machined again.

My 96 had a leak on the passenger side too. Van came from Iowa. My guess is that snow/ice buildup occurred here with road salt that caused the manifold to corrode from the salt.. I replaced them with shorty headers when I did the GT40 head swap. Bolts came loose easily when I did the swap.