I have the mechanic coming over who did the rebuild. On the phone he
told me that if the boat had not been run for six months (since the
rebuild was completed), that rust may have built up in the cylinders,
or on the valves, and that this might account for the oil pressure
problem. Does this sound reasonable?



jamesgangnc wrote:
Only reboring one cylinder is not completely unheard of in the diesel
world. That doesn't explain your oil problem. But I suppose could be
indicative of a less than stellar rebuild job. If you got a detailed
invoice for the job you might be able to see the parts list and see if
a new oil pump is on it. If you paid for a rebuild then it should have
oil pressure. At a minimum it should have the oil pressure it had
going into the job. But really it should have better since they should
have replaced all the bearings.

wrote:
Thanks for the educated response. I'm waiting on a call from the folk
who did the rebuild. The problem is that one mechanic started the
job and another finished it. Given that scenario, it sounds like that
plug may have been opened by one, and not known by the other.

The other suspicion I have is that only one piston was replaced, as it
was cracked. The other piston and cylinder wall looked fine, so I
think he may have put it back together without re-boring the second
cylinder.

jamesgangnc wrote:
It's could be a bad pump but that is normally unlikely. Did you
replace it as part of the rebuild? Typically that is part of a
rebuild. Oil pumps are simple mechanical devices so they don't usually
go bad. One problem can be that a piece of crud gets caught in the
relief valve and holds it open. The other possibility and most likely
is that one of the oil passageways in the block was not closed back up
during the rebuild. Normally you removes passageway plugs before the
block gets machined and tanked so it gets as clean as possible.
Sometimes leaving one out can result in all the oil just running right
back into the pan.

If you crank it for a second with the oil filter off and a bucket under
it you could get an idea if the oil pump is doing anything at all. If
oil comes out I'd put my finger over the hole and try it again to see
if it's got any pressure at all. Messy but something to try before you
tear it down.

I would really try to not run it at all until you figure it out.
Bearing wear is very rapid without oil pressure.


wrote:
Thanks for the response. My mechanic has already put his gauge to it
and confirms
no oil pressure. Could there be a bad pump, or some other
explanation?



jamesgangnc wrote:
Put a mechanical gauge on it and make sure it's not a gauge problem.
Don't run it any more until you know. It won't make any unusual noise
until the bearings are shot and then you get to rebuild it again.

wrote:
I have a recently rebuilt Unversal 5418 two-cylinder diesel. My
mechanic started the boat last weekend and noticed there was no oil
pressure. The engine runs and sounds just fine.
Has anyone ever had this problem? Any experience ? Should I curl
up in the fetal position? I just spent 4,000 to have this engine
rebuilt.