Lower Crank Seal 78' - 175HP

[Numlaar]

Hey all,

Background:
OK so I have a 1978 FrankenMotor...

It had previously burned a piston on #6 (bottom left). When I pulled it apart it had some grayish milkish liquid residue in that cylinder, and I didn't think much of it. Put in a new piston and put it all back together, now I am getting that same grayish milkish liquid, but a lot more of it (the new piston is NOT breaking down, yet), but probably because i have only about 30 mins run time on it so far.

I gave up after pulling the head, exhaust plate, and bypass covers, and everything looked good (including piston and cylinder). Also when I had it apart to replace the piston, I honed the cylinder, and the sleeve all looked good as well, so I do not think it's a cracked block.

I took it to a local shop, They re-pulled the head, exhaust plates, and bypass covers and agree they were all sealed and fine... They are now saying they have to pull the powerhead, and that if it isn't a cracked block, its the lower crank seal... (When i replaced the piston, I just slapped it back together with the old seal, so this was NOT CHANGED).

My questions:
1. Can a bad lower crank seal cause #6 to suck (suction) back up water somehow?
2. In order to replace the lower crank seal, do they have to re-split the crankcase, or just put in a new seal? (1978' 175HP crossflow)
3. Any other thoughts on what might be causing this gray milky sludge in #6?

 

[emdsapmgr]

Re: Lower Crank Seal 78' - 175HP

Not sure that a weak lower crank seal would cause a water access to the #6 cyl. Check your inner exhaust cover (manifold.) I went through the same thing, but on an 83 235 block. Got water in #6. Tore down the exhaust manifolds looking for areas of leakage around the gaskets/seals. Worst was I had to tear it down twice looking for the source of water-which was not apparent from my visual inspections. Finally inspected the inner exhaust cover and found it was a porous casting-a hole about the size of a pencil eraser was letting water into the exhaust chest from the rear water jacket. Was very apparent when I shone a light from behind the manifold. Had it aluminum welded and it's been fine ever since.

 

[Numlaar]

Re: Lower Crank Seal 78' - 175HP

Not sure that a weak lower crank seal would cause a water access to the #6 cyl. Check your inner exhaust cover (manifold.) I went through the same thing, but on an 83 235 block. Got water in #6. Tore down the exhaust manifolds looking for areas of leakage around the gaskets/seals. Worst was I had to tear it down twice looking for the source of water-which was not apparent from my visual inspections. Finally inspected the inner exhaust cover and found it was a porous casting-a hole about the size of a pencil eraser was letting water into the exhaust chest from the rear water jacket. Was very apparent when I shone a light from behind the manifold. Had it aluminum welded and it's been fine ever since.

OK thanks, I will let the shop know... I do believe however, that the exhaust plate (inner and outer) are from a different motor than the one that is experiencing the problem.... so it wouldnt make sense for that to cause the same issue as before, now.

He did inspect both pieces and said they were fine as well as the gaskets being sealed, he said the only two options left are cracked block, or bad seal causing it to suck back... (his words not mine).

 

[emdsapmgr]

Re: Lower Crank Seal 78' - 175HP

I'd be interested if the heads on that block are perfectly flat. They need to be for proper sealing of the head gaskets. Heads do warp, esp if the engine was severely overheated at some point in it's life. I've seen brand new factory heads out of the box that were not flat. Were the heads retorqued to spec after the engine went thru a couple of heat/cool cycles?

 

[Numlaar]

Re: Lower Crank Seal 78' - 175HP

I'd be interested if the heads on that block are perfectly flat. They need to be for proper sealing of the head gaskets. Heads do warp, esp if the engine was severely overheated at some point in it's life. I've seen brand new factory heads out of the box that were not flat. Were the heads retorqued to spec after the engine went thru a couple of heat/cool cycles?

Yes they were, and put on a straight edge, and the shop said the head was fine, and head gasket was sealed Also the heads are off a different engine, so again shouldnt be the reason for the issue (at least as far as I can tell)...

guess I am just a little frustrated... I have 500 bucks into them taking this apart and they have told me everything is good so far that they can see... just would think you woudl be able to tell why water getting into the cylinder before all this...