Overheating 5424

[Jason]

Hey All,

I have the Universal Atomic Diesel 5424.

Motor was running fine in the clear waters of Lake Michigan after motor sailing for 3 hours, then the engine overheated.

I thought it was the impeller. Poped off the cover, impeller is fine. Plenty of coolant in the freshwater system and a good impeller in the raw water system.

Could the thermostat just got stuck closed after hours of running fine?

Is there a pump in the freshwater system? (gotta ask)

Thanks for any help

 

[Os Saguil]

chech the thru hull raw water intake, make sure it is not plugged with seaweed or a plastic bag sucked into the thru hull. If you remove the rubber hose connecting your sea cock to the raw water intake should have a water fountain streaming in at least 3 inches, don't panic to stop it close the sea cock. if water does not stream out poke a wire hanger or a devise like a roto rooter down the seacock to the thur hull, whne you pusk out whatever is blocking it, water will stream in and sail agian.

 

[NateHanson]

I'd offer one modification to the plan Os suggests above: CLOSE THE SEACOCK FIRST! That way you won't discover after you've removed the hose that the seacock is frozen open. You can close the valve, remove the hose, open the valve, and see what comes out.

 

[Shadowfax]

By fresh water I assume you mean the water in the engine itself and yes there is a pump. It is behind the top pulley. They do go bad, but I'd look at the thermosat like you said, then the heat exchanger to make sure something isn't cloged in there, then the riser which can get carboned up.

Good luck

 

[Jason]

I did close the sea cock when I removed the cover to the impeller.

Order of what I'll try:
1. Make sure raw water intake is not blocked.
2. Try to crawl back by heat exchanger, remove "out" raw water line to insure it is not clogged.
3. Check the riser.

It's that last one, assuming I get there, how do I check it?

Thanks!

 

[NateHanson]

If the riser were clogged, wouldn't the engine be showing signs of excessive backpressure?

For the heat exchanger, I'd probably check the "in" end of it, because that's where all the junk accumulates to block the little tubes. If there's nothing there, you're probably not clogged. you could stick a plastic wire tie through some of the tubes though to ensure that they're not crusted up inside.

 

[Shadowfax]

If your riser is like mine [E34 with a 25 XP] you will see a hose attached to a elbow fitted into the riser near the top of it. Remove the elbow and take something like a screw driver and move it around the inside of the riser where you removed the elbow. If it is clogged, you will find black glop in there that the screw driver will break up. Put it back togeather, start the engine and observe black glop exiting the exhust.

The system itself is simple. I'd start where you have started, the through hull, and work my way through the system. Also, check the fan belt tension. It could be as simple as that

 

[Jason]

1. Make sure raw water intake is not blocked. (Checked A-OK)
2. Try to crawl back by heat exchanger, remove "out" raw water line to insure it is not clogged. (Checked A-OK)
3. Check the riser. (Not Checked)

It is pumping water out starboard water outlet a-otay.

I did not run it long enough to overheat, but I know this, the problem is not on the "raw" side.

 

[Mike.Gritten]

Jason,

Last year I had a minor overheating issue that was resolved by replacing the cooling system pressure cap (like a rad cap on your car). Ours was only 4 or 5 psi, I forget which now, but made a heck of a difference when installed. It appears that on our original cap, the spring had weakened over time and was not sealing the cap to the housing allowing the system to run with only normal atmospheric pressure - not so efficient!

 

[Emerald]

I've had issues (on other engines) where I had an air pocket trapped and needed to bleed the heat exchanger side of the system. Very simple you need to open something up at the highest point in the system and fill your coolant level until it comes out of this opening. I will warn that depending on the system, this might require the thermostat to be opened, whereupon you'll need to run the engine warm enough to do so, whereupon do be careful about getting sprayed/burned by hot water.


-David
Independence 31
Emerald