Over heating with a load on

I have a bayliner 3888 with US marine 351 ford engines. My port eng is heating up when I put any kind of load on it. At the dock it runs fine I checked to make sure it was pumping water out of the exhaust.

I have been having an issue keeping antifreeze in the heat exchanger. Could that be the issue?

I don't think it is the impeller because it pumps water at idle.

Has anyone had a heat exchanger repaired or replaced, if so can I get the name of the place.

Thanks Much!

Mike and the admiral Karen

You may have a blown head gasket. Check compression.

would the oil show if a head gasket was blown?

A significantly worn impeller will still likely move water at idle. But crank up the load and it might not have enough meat left on the fins to pump enough water. When's the last time you checked/changed it? That's a simple and relatively inexpensive starting point.

It's very likely if you had a blown head gasket that water would get into the oil. The oil on the dipstick would show up as a lighter shade than usual, with a milky appearance to it.

But if you've got a leak in the exhaust risers or heat exchangers those would allow coolant to escape. That typically shows up as a more white-ish amount of 'steam' to the exhaust. There might also be a more slippery feel to the exhaust ports, and possibly some sheen on the water.

When's the last time the heat exchanger and/or risers were serviced?

As for names/places... it helps if you update your profile to include a location.

https://www.trawlerforum.com/forums/profile.php?do=editprofile

You would be surprised at how damaged an impeller can be and still pump water at idle. One guy recently reported an impeller which looked OK and kept the engine cool enough at low speeds. However, the brass center of the impeller had spun, much like outboard motor props can do such that when the engine was sped up, the engine overheated because the impeller blades were not working at rated capacity if they were even spinning at all. Since you are having issues with the coolant level, this MAY not actually be your problem, but impellers are relatively cheap to replace.

Borrow a tester from your local auto parts store to test for exhaust gases in your coolant.

I will third omme about impeller

My first thought would be the impeller as mentioned above. Secondly, failed head gasket does not necessarily put coolant in the oil.

Had a similar issue with my starboard engine this weekend. Suggest you take a look at the belt tension for the fresh-water pump. Mine was quite loose and may have been the culprit. (Full disclosure, haven't tightened the belt or tested the 'fix' yet, so I may be wrong, but still, something to look at).

OK thanks to ALL! I will try to get down check the impeller and the belt. I am for sure thinking the heat exchanger needs some repair of some sort. I have run about 3 gals though it going out 3 times..
The boat is kept in Niceville FL.. I will update my profile...

See if there is bubbling or evidence of exhaust gas in the coolant. A failed gasket does not have to mix coolant and oil but can blow out coolant.

Compression check before things get worse.

Mike3888 said:

OK thanks to ALL! I will try to get down check the impeller and the belt. I am for sure thinking the heat exchanger needs some repair of some sort. I have run about 3 gals though it going out 3 times..
The boat is kept in Niceville FL.. I will update my profile...

Click to expand...

Is it going through that much during the course of going out? As in, it's at one point when you start and then dropped significantly by the time you're back? Or is it losing the coolant while you're away from the boat? Though, I suppose, both mean it's got issues that need to be addressed, but from a diagnostic perspective it matters some.

If you're not certain of the impeller's age and condition it's probably one of the simpler DIY repairs for most engines. Likewise belts. They're among the least expensive things you can replace on an engine, but if they fail can contribute to significant repair costs. You should generally keep a fresh spare on board, and rotate that through your replacements. I've tended to replace mine every other year. Keeps the spares fresh that way too.

I have loaded my tome about overheating problems below. Look through it.

Secondly , if there are other symptoms out of the ordinary then fill those in also. THere may be a very important clue you haven't told us such as the mention that you have lost substantial coolant several times.
Be clear.


One way to check for a blown head gasket is to use a 5 gal bucket filled with water. Use the overflow hose at the side of the filler neck and lead that hose into the bucket so the end is well below the surface. You may have to tie a weight to it to ensure it stays near the bottom.

How much coolant loss and when? How are you filling the heat exchanger? to the absolute brim of the filler neck?

Secure the bucket so it does not slide and dump.

Run the engine warming it fully. THis will be a run, not the dockside operation.
There will be bubbles as the engine warms and the coolant expands driving out any air. THose bubbles should subside fairly soon after full warmup. There may be a few now and again.

If there is a steady stream of bubble continuing after full warm up then the likelyhood of a gasket problem is high.

tiltrider1 said:

My first thought would be the impeller as mentioned above. Secondly, failed head gasket does not necessarily put coolant in the oil.

Click to expand...

But can put oil and exhaust gases in the coolant. The tester method is easiest.

C lectric said:

I have loaded my tome about overheating problems below. Look through it.

Click to expand...

That's a pretty exhaustive list. Thanks for posting it.

Assuming your oil is not milky.
The most obvious choices first.
1) Replace the impeller. Cheapest and quickest solution.
2) Replace ( not boil out) your heat exchanger. I firmly believe, like engine mounts, these are throwaway items. They should be replaced periodically. (Every 10-15 years) Lenco, on Long Island, is a fantastic source for heat exchangers.

Mike3888 said:

I have a bayliner 3888 with US marine 351 ford engines. My port eng is heating up when I put any kind of load on it. At the dock it runs fine I checked to make sure it was pumping water out of the exhaust.

I have been having an issue keeping antifreeze in the heat exchanger. Could that be the issue?

I don't think it is the impeller because it pumps water at idle.

Has anyone had a heat exchanger repaired or replaced, if so can I get the name of the place.

Thanks Much!

Mike and the admiral Karen

Click to expand...

The usual suspects are well covered. coolant is circulated through heat exchanger. Failing impeller, clogged exchanger, clogged intake.
351 Ford engine.
Sounds like gas engine with plugs and timing needs. If yes, Maybe it needs a tune up, could be running lean etc.

Any radiator shop should be able to test and repair a heat exchanger.Any engine running in salt water needs the scale and marine growth flushed on a regular basis.
Rydlyme and Barnacle Buster are common solutions for flushing.

would the oil show if a head gasket was blown?

Click to expand...

It may or may not.

A big gap in the gasket would allow coolant to drain into the cylinder then into the lube oil and also possibly hydro lock the engine. A small pressure sensitive gasket leak might only allow combustion gasses into the coolant passages under higher pressures until it fails completely. Then you will see water in the oil.

Compression checks are not hard to do and may save a lot of money or prove that the problem is raw water flow.

To ALL thank you MUCH! I will try to do as many of the possibilities as I can. But problem is if you send me for a left handed screwdriver I would go looking..
Hoping it is something small but the list of possible causes maybe beyond my capability. Guess that is way there are boat repair shops in business.
Again cant say thank you enough I will update when we find the cause!
Mike and the Admiral Karen