Universal M25XP problem

[pzmaria]

Hello all members. I just became a proud owner of my first C30 and I'm quite new to the engine that is installed on this boat. It's an older model from 1987. It was never used extensively as far as I was told and engine hours were not excessive. She has a Universal M25XP. She was an a way from western Florida to Dry Tortuga National Park in Key West. Due to the weather conditions we had to use engine for about 15-20 hours. At some point the engine got hot (200-220 deg) and was shut down. Hard to tell how long it was running at this temperature as a guy at the helm didn't check the temperature gage. It was the smell of overheated engine that caught our attention. During the first investigation we noticed that there was no water coming from the stern so definitely raw water system problem was causing overheating. water pump">Raw water pump was checked, impeller checked - all good. We had no time to check the heat exchanger where I suspect is the problem - please correct me at anytime if my conclusions are wrong. Right now she is back to the dock in Florida and I had to go back to Canada. What I was able to check before leaving was exhaust pipe all the way from the stern to the wet muffler - no blockage, no obstructions. There is no water on the oil dipstick. What worries me is some traces of oil in the coolant overflow container. It is possible to start the engine but exhaust fumes are coming from air intake filter.
I'd like to hear from owners experience what I can expect when repair time comes.
Is it just a head gasket or should I be prepared for worse? I want to start gathering parts required for repair before I go back to the dock for repair. Thank so much for any input and advice.

pzmaria

[Diesel Bill]

If the water pump impeller was still good, (replace it any way) It might have sucked air from a faulty sea strainer cover gasket/o-ring. The pump cover gasket could have leaked air. Might have a loose hose or a pin hole leak in the suction hose. Could have picked up a piece of plastic that blocked the suction. The over heated engine will puke all kinds of dirty sludge and oily residue into the over flow. Did the engine seize? Sure didn't do it any good, but you might have not killed it. If you're getting exhaust blowing out the air inlet could be head gasket or tight valves or warped head or scored cylinders
from running hot with a heavy load, maybe not. Top off the coolant and if it starts will it pump sea water out the back now? Does it run smooth or rough? Might have to break the suction hose off the pump and prime the hose and pump. It's really hard to do a diagnosis with out being able to see it in person. Good luck and let us know what you find.

[mogulskibum]

These engines are really hard to seriously hurt. That's the very good news.

The other good news is that except for a few of the marine specific parts, you can buy kubota parts from a tractor dealer. This really, really lowers the costs of any engine repairs (and even maintenance is a lot cheaper). For example: Kubota head gasket: $50-70, Universal head gasket: $135-150.

The kubota engine is the D950 - I *think* I have a pdf with all of the Kubota part numbers that I can send you if you send me a PM (I know I have the D850 - which is the Universal M25).

My guess, without seeing your engine, is that you have a problem in the heat exchanger. There's a pencil zinc that needs to be changed regularly - it should be changed even before it wears out, because it can wear in an odd way: at the base first. I've seen cases where the base wore out (think of a tree being felled by a beaver), and then the top of the zinc floats around and blocks off several of the tubes.

But more likely the heat exchanger is just clogged up with gunk after so many years. Take it off, and bring it to a radiator shop where they can dip it acid to completely clean it out. Replace the seals at the end (seeing as the heat exchanger is part of the marinizing, there is no kubota equivalent - so these will have yacht pricing rather than tractor pricing), replace the pencil zinc, repaint with a self-etching primer (spray can), and engine paint (another spray can).

The good news is that if you don't have water coming out the back, there's not much to check.

Is water getting to the pump? That's easy, take the hose off the pump, open the seacock and see if you get water (don't forget to re-attach the hose)

Is the pump pumping water? It's almost a direct shot prom the oberdorfer seawater pump to the heat exchanger (two hoses and an elbow) - take the hose off the heat exchanger, open the seacock, and crank (or even start) the engine and see if water is getting to the heat exchanger.

Is water getting through the heat exchanger? The seawater goes directly from the heat exchanger to the exhaust elbow, disconnect the hose from the exhaust elbow and crank or start the engine.

The worst case scenario is that the heat exchanger is completely shot and a radiator shop can't get it cleaned out. Seakamp makes a replacement - it's $300 - or you can pay ~$400 for a universal.

Note: if you do replace the heat exchanger, universal used two different ones over the years, a 2" one and 3" one. You need the 3" one, the 2" one isn't effective (there's a reason they changed it).

Also, and this is very, very important (and completely unrelated to the current problem): double check that you don't have the old style alternator bracket! Read here for why:
Universal M-18 & M-25 Alternator Bracket Upgrade Photo Gallery by Compass Marine How To at pbase.com

That page is from Mainesail's website. The majority of the engine projects he shows on his page are from Universal M25s. You'll want to reference it often:
Welcome To MarineHowTo.com Photo Gallery by Compass Marine How To at pbase.com.

He even has a page delving into the heat exchanger:
Autopsy A Westerbeke / Universal Marine Heat Exchanger Photo Gallery by Compass Marine How To at pbase.com

[Tetepare]

A filled muffler will stop water flow.

This problem should be easy to trace. Start disconnecting hoses from front.

[pzmaria]

There was no oil in overflow container before, haven't notice any. Right now there are just traces on the container walls in the form of white sediment. As for the exhaust fumes it is not just the smell, they are coming from air filter like from the muffler in great quantities. Forgot to mention that when I started the engine after this whole ordeal it sounded different, something like knocking sound in gasoline engine with low octane fuel.