Engine rebuild issues

[BahamasBlair]

Hi,
I just had my port side engine taken apart due to water ingestion by corroded exhaust manifolds. My mechanic changed the manifolds, had the heads machined, replaced all the gaskets, etc, etc. She starts perfectly and sounds fine. Concern i have is that both the oil pressure and water pressure are much lower than the other engine.
The untouched engine run at about 55-60PSI on the oil at 3000RPM and about 7PSI on the water at idle. The redone engine gets 36PSI max on oil at 3000RPM and 0.0 PSI at idle.
Something must be wrong.
Does anybody have any suggestions?

 

[tobnpr]

I assume you've already asked the mechanic- what's his take?

Stating the obvious- zero oil pressure ain't a good thing. I hope you're not running it...

First thing I'd do is swap the gauge from the port engine to the stbd. to rule out a defective sender.

How much water was in the engine- was it just water in the cylinders, or did some make it into the bottom of the engine? This is a bit out of my knowledge comfort zone, but seems that if a substantial amount of water got into the pan- it could have damaged the oil pump, given that the water would obviously settle to the bottom of the pan...where the oil pump lives.

 

[BahamasBlair]

Hey thanks, thats a good start.
I will swap the senders tomorrow and see what I get. For oil pressure i'm getting at least 35PSi but not 55PSI like the stbd side.
Zero water pressure at idle versus about 5PSI on the stbd engine.
Thanks for the input. Much appreciated. Regards, Blair

 

[BahamasBlair]

By the way, that is a great looking helm - did you build it?

 

[fc3]

You can put an ohm meter on a standard oil pressure sender. Read the resistance and convert to PSI. Eliminates wiring and the gauge as problems. There are two types of senders. Single station senders are meant for boats with one helm and one oil pressure gauge. Dual station senders are for boats with two helms and therefore have two oil pressure gauges. You want to read the single resistances.

If you actually have an oil pressure problem, and it sounds like you do, it should not be a major problem. I'm going to assume your mechanic did not do a full rebuild, but just pulled the heads. There's a couple of places that you can lose pressure from the top end. Could be the distributor drive lube passage or the hydraulic lifter passages. If one of those parts is bad or somehow installed incorrectly, you'd lose some pressure. I don't know how the 8.1 lubricates the upper end of the valve train, the rocker arms. I think there is an oil passage, I don't think the push rods are hollow. The mechanic might have munged up the gasket for one of the passages between the block and head, causing a leak and loss of pressure. You don't know until you pull it apart.

The worst possiblity? You had enough water in the engine to errode the main bearings, where the engine is leaking too much oil around the worn bearings. Of course, the bearing would have to be pretty worn for this to be a problem and you'd probably have other symptoms.

 

[OldSkool]

You can put an ohm meter on a standard oil pressure sender. Read the resistance and convert to PSI. Eliminates wiring and the gauge as problems. There are two types of senders. Single station senders are meant for boats with one helm and one oil pressure gauge. Dual station senders are for boats with two helms and therefore have two oil pressure gauges. You want to read the single resistances.

If you actually have an oil pressure problem, and it sounds like you do, it should not be a major problem. I'm going to assume your mechanic did not do a full rebuild, but just pulled the heads. There's a couple of places that you can lose pressure from the top end. Could be the distributor drive lube passage or the hydraulic lifter passages. If one of those parts is bad or somehow installed incorrectly, you'd lose some pressure. I don't know how the 8.1 lubricates the upper end of the valve train, the rocker arms. I think there is an oil passage, I don't think the push rods are hollow. The mechanic might have munged up the gasket for one of the passages between the block and head, causing a leak and loss of pressure. You don't know until you pull it apart.

The worst possiblity? You had enough water in the engine to errode the main bearings, where the engine is leaking too much oil around the worn bearings. Of course, the bearing would have to be pretty worn for this to be a problem and you'd probably have other symptoms.

I must agree with you on this. The bottom end should have been disassembled and inspected. The oil pump, rod and main bearings and connecting rods all should be checked. Oil pump and main bearing are leading cause of poor oil PSI.
I am a bit concerned that you are only running 5LBS on the stdb engine. How many hours do you have on these engines?

 

[skolbe]

0 water pressure is hopefully the sensor - but you need to fix it or it will be in guardian mode. FC3 has given some good info on the rest.