Cracked/Leak in Block??

[gdasw]

I have been struggling with water in the oil since at least the middle of the summer. I have tested my compression and have 90-90-100-100 PSI. I pressure tested my exhaust manifold and it seems ok. I also did a pressure test on the block and it appeared to be ok, although I did not drain all the water out of the block first.

I thought it was an exhaust system problem since my cooling water was injected into the exhaust at a point that was close to the exhaust manifold and I did find some water in the exhaust manifold at the exhaust end. I have since moved the water injection point lower and I don't think that this is the issue.

I did a second block pressure test today after draining all the water from the block. During this test the pressure started to drop after about 10 minutes so I am suspecting that I may have a leak in the block somewhere. I removed the plugs from the cylinders but could not hear any leaking air. I removed the transmission plate and could not hear anything there either.

My engine starts easily and runs well and I have not found water in the cylinders.

The engine serial number is 195,nnn so I am wondering if it could be the issue with the plug on valve side. I will check that.

If I do have a block leaking issue, what are my options. Are leaking blocks common? Is this something that is fixable? Do I have to pull the engine and totally pull it apart or just partially?? If I have to, should I start with the head first?

Thanks,

Geoff

[Don Moyer]

Geoff,

If you are only getting a small amount of water into the crankcase, given your good performance and successful pressure test of the block (at least your original test), head, and manifold, I suggest you focus on your water pump.

We have had three cases in the past year where the shaft seals in water pumps have allowed small amounts of water to move along the shaft and into the crankcase. Two of these pumps were Oberdorfers and the other an MMI flange pump. Since these pumps are designed with large weep holes in the housing, we have historically thought it impossible for them to introduce water to the crankcase (the water would simply run out the weep hole and into the bilge).

Bottom line: When all other sources of water have been explored and eliminated, we now recommend rebuilding or replacing the water pump before moving to more serious maintenance work on the engine itself.

Don

[gdasw]

Thanks for the reply Don. I believe the water pump is an MMI flange pump. I am not sure when it was installed. We will be hauling out this weekend so I will pull the pump and check the seal. To rebuild it should I order the flange repair kit CSOB_00_461.

Geoff

[Don Moyer]

Geoff,

Yes, if it is indeed an MMI Flange pump, that would be the kit.

Don

[gdasw]

Water Pump

Don, I ordered the MMI pump rebuild kit because I thought I had a MMI flange pump but when I took it apart the rebuild parts didn't seem to mesh. There is no MMI name on the outside of the pump. There are 2 numbers stamped on the outside, 404 and 405, it has a quick change plate on it and the impeller does not have a snap ring on it. Is this a later model orberdorfer or something?? The seal on the inside has orberdorfer on it and number A5463. Should have I ordered the orberdorfer seals??

Thanks
Geoff

[Don Moyer]

Geoff,

I can't be sure of what model pump you have, but to be sure, if it has Oberdorfer seals you would have to order Oberdorfer seals to replace them.

Don