Closed Cooling System on Port Engine Running Hot(ter)

[tpenfield]

UPDATE:

OK, I took today off to hopefully fix the cooling issue . . .

I got a new thermostat and tested it on the stove. Starts to open at 160 F and wide open at 170 F

I got some CLR and some Kaboom

So, the 'plan' is to got out to the boat (mooring) and pull the HE again. Clean the holes, etc. Replace the thermostat. Put it all back together and go for a test run.

I can then test the original thermostat back at the house to see if it was the culprit.

 

[tpenfield]

A Quick update and some photos ('cuz folks like photos, right ?)

I removed the heavy scaling chunks and then put liberal amounts of 'Kaboom' down through the HE.


Digging a bit deeper into the cooling system, I took the thermostat housing off to replace the thermostat. I also checked disconnected/reconnected the sender wiring. The wire on the housing itself is for the overheat alarm. The one on the plumbing is for the ECM and gauge.



Here is the original t-stat with the 3 by-pass hole that I drilled in the flange. They are to provide some cooling for the exhaust manifolds before the engine gets to temperature.



Here is a pic of inside the intake manifold water passage. pretty clean for a 20 year old engine . . . no scaling, just surface rust.



Here is the new thermostat with 3 smaller by-pass holes



Here is the HE detail where there was a calcium build-up. In total there were 7 holes blocked. I am wondering about the starboard engine at this point and if I will see a build-up there. That engine seems to be fine



All put back together . . . but I have to go back to the house and get a strainer to use for pouring the coolant back into the HE/engine.



Today and for the next few days it is a really high and low tide. The rock that is just aft of my mooring is showing quite a bit, and the keel of my boat is slightly touching the bottom of the basin.



so I gotta wait a few hours to get back some more water so that I can test these latest set of 'fixes'. Back to the house for lunch . . .

So, while at the house, I tested the original thermostat . . . works fine !!! :facepalm: So, it better be the HE or else I am at a loss.

 

[tpenfield]

Thunder storms rolled in by mid-afternoon. So, I was about to head out and test the boat, but I checked the radar image and it showed a t-storm bearing down on my harbor. So, I packed it in for the day.

 

[tpenfield]

Update:

Marginal improvement on the port engine . . . probably due to the HE cleaning. So, I still have an issue with the cooling. On the outing today, the port engine ran 170-175, while the starboard was 155-165. So, tomorrow, I am going back through the raw water side.

I'm wondering if there is a recirculating pump issue?

 

[tpenfield]

Ah phooey. . .

I have been beach-bound the past 2 days, still trying to resolve the port engine cooling issue. Today I took the water intake hoses off of both the oil cooler and the ps cooler, and back flushed them both. I did not find any clogged material or anything. Then I ran the engine with the hose still disconnected from the oil cooler to check the water flow from the sea water pump. Looked good, I then backed flushed the intake hose leading to the seawater pump, it seems fine.

The closed cooling system is holding pressure.

The port engine is still running 20 degrees hotter.

So, off to the beach to chill out with a few cold ones.

Plan for next week is to swap the gauges. I could try to get a new sender in time for the weekend.

If I do a new sender, I think I will put the original thermostat back in, because I like it better.

Remove the recirculating pump and check the impeller. Re-check the exhaust elbows,

I might try to snake the intake line that goes through the transom assembly. Once I had a barnacle get lodged in that section of hose.

??? I may open up the exhaust tubes to inspect the flappers. I am wondering if there were a restriction in the exhaust if it would also restrict the flow of the sea water from the cooling system ???

Any other ideas :noidea:

 

[achris]

Have you checked engine timing? And advance curve.

 

[tpenfield]

Have you checked engine timing? And advance curve.

I have not, but can put that on the list of thing to check. Engine performance does not seem to be any different than before. Let me know any specific thoughts along the engine timing lines.

I went out to the boat again later today to try a few things. Swapped the gauges. No change, so both gauges are good.

I may try to get an infrared gun this week to see if that can tell me anything. I still don't know if the issue is on the 'closed' side or the sea water side of the cooling system.

 

[achris]

I wonder if it's possible to measure the water pressure of the seawater at the inlet of the HEs. If you have a restriction in the HE (seawater side) that would reduce the flow through the HE, leading to what you see. That may at least tell you seawater or fresh water side.

Chris......

 

[tpenfield]

I wonder if it's possible to measure the water pressure of the seawater at the inlet of the HEs. If you have a restriction in the HE (seawater side) that would reduce the flow through the HE, leading to what you see. That may at least tell you seawater or fresh water side.

Chris......

Yes, I would think that if there were a reduced flow of sea water through the HE, then the pressure at the inlet would be higher due to the restricted flow. I think for now, I'll try to get a heat gun.

All 4 elbows are warm, but not hot. I can leave my hand on them. I was thinking of getting the adhesive temperature strips to put on the elbows to see if there is any significant differences between them. Also, if the elbows are a reasonable temperature, it might indicate reduced flow on the coolant side of the system and a correspondingly higher operating temperature to remove the same amount of heat from the engine.

I think my next step is to remove/inspect the recirculating pump.

 

[glennj3]

Nice job, question for my personal information. Does the radiator fluid run through the tubes does the lake water run through the tubes? I am trying to test mine for a leak off of the boat. Thanks,

 

[tpenfield]

Nice job, question for my personal information. Does the radiator fluid run through the tubes does the lake water run through the tubes? I am trying to test mine for a leak off of the boat. Thanks,

I just which the 'job' were done at this point. In terms of your question. The chambers and tube openings that you see in the H.E. pictures that I posted have sea water running through them. The coolant basically surrounds the 'grid' of tubes between the end chambers in order to exchange the heat.

 

[tpenfield]

I picked up an Infrared Thermometer at HD. So, next weekend I will be able to better isolate the issue by looking for the heat and comparing similar points on each engine.

 

[glennj3]

Yeah, it can be confusing. One would think that the sea water would circulate around the tubes because of the trash could lodge inside of the tubes easier than inside of the larger tube. Mine also has a drain at the bottom for winterization which drains the tubes system, which would be the antifreeze. Does not make sense to me? But then the thermostat opens and sends antifreeze through the HE, into the larger tube, not the smaller tubes? So I am confused. Sorry, just trying to figure it out. Hope you find the problem there!

 

[tpenfield]

I noticed that you have a thread started about your heat exchanger. I'll take a look and add comment if I can offer any help.

 

[tpenfield]

Another weekend, another set of diagnostics to try . . .

Kind of cloudy today on Cape Cod (aka Cape Cloud ). So, I will spend some time doing additional diagnostics on the cooling system. I bought an infrared thermometer at HD to see if I can better isolate the source of the problem.

My plan is to run both engines up to temperature and check various points on both engines for comparison. Then see what that tells me.

My Thermodynamics and Heat Transfer books from college are all up in the attic (somewhere), so I am just going to have to wing it . . . . . . . But my thinking is that if the sea water exiting the engine is about the same temperature on both engines, it would indicate that the problem is on the closed (coolant) side of the system. If the sea water temperature is hotter, it would tend to indicate reduced sea water flow. (sort of a 'Mass' x 'Temperature' thing)

Other things that I can and may do, beyond what I have already done, are:

1) Snake the intake line at the transom to see in there is anything stuck in there
2) Remove/check the recirculating pump
3) Check the hoses leading to the exhaust manifolds

We shall see how it goes . . .

 

[tpenfield]

UPDATE:

I worked on the boat for the morning, checked the temperatures after warmup and did a few things. Then I took the boat out this afternoon, as the seas were flat.

I took a bunch of temperature readings and the port engine is definitely running about 20 degrees hotter than the starboard engine on the coolant side. The sea water side on the port engine is running about 5 degrees hotter than the starboard engine.

Here are a few pictures . . .


The engines




The gauges






The infrared temp gun.






Here is a schematic of the Engine and the locations where I took the measurements




Here is the table of the data that I recorded from the temp gun. These were all after the engine had been running for about 30 minutes. The values below are degrees F.



I am thinking that the problem is more on the coolant side than the sea water side . . . BUT . . . the slightly higher sea water temperature upon exit from the engine may indicate a problem as well:noidea:

I did not have time to take the recirculating pump off for inspection. I did remove the sea water strainer for a through back flushing and I also snaked the intake line through the transom to see if there were anything clogged in that section of the line.

The engine ran a little bit cooler . . . 170 ish vs 175-180 previously, but the starboard engine still runs 155-165.

:facepalm: Looks like I'll be at this again tomorrow. TIA for any comments/thoughts about the temperature readings.

 

[achris]

Try gently restricting the outlet of the HE on the stbd engine to get the exit water temp to the same as the port engine. See if the other temperatures correlate.
Just a throught...

Chris.......

 

[tpenfield]

Try gently restricting the outlet of the HE on the stbd engine to get the exit water temp to the same as the port engine. See if the other temperatures correlate.
Just a throught...

Chris.......

Good thought . . .

Just playing with the numbers . . . the Port HE is reducing the coolant temp by 87 degrees while the starboard engine is reducing the coolant temp by only 70 degrees, as it is running cooler.

The port engine coolant is gaining more heat as it goes through the engine (average of 16 F vs. 10 F for the starbd engine. It seems like the temp increase through the exhaust manifolds is consistent between the 2 engines.

 

[tpenfield]

Morning Update:

Another cloudy day, so I'll have some more time to work on the engines.

Chris - I have some clamps that may be useful in restricting the flow of sea water through the system. I could also use the clamps to restrict the coolant side to see which better correlates to the temps that I am seeing on the port engine.

I added some calculations to my spreadsheet of temperature data (yellow area at the bottom). . . basically looking at how much the temperature rises/falls in the critical portions of the cooling systems.

Three points of interest in the figures:

1) The port Heat Exchanger is doing a pretty good job taking the heat out of the coolant, since it cools the coolant by 87 F versus 70 F on the Starbd engine. So I am thinking the H.E. is in good shape.

2) The port engine coolant is definitely gaining a lot more heat as it goes through the engine than the starbd engine.

3) The coolant as it goes through the exhaust manifolds are gaining the same amount of heat on each engine . . . which I find odd given that the coolant going through the port engine is getting a lot hotter than the starbd engine. I would think that if the overall coolant flow were restricted/reduced on the port engine, then the temp rise through the exhaust manifolds would also be greater. I am wondering if there is an isolated restriction within the engine block and the coolant is not circulating as well through the block and bypassing more directly to the exhaust manifolds?

Or . . . could the port engine be creating that much more heat? :noidea:

Chris - you mentioned timing as a possible issue. (I forgot to bring my timing light with me) Maybe I can get one in town.)

Or . . . If it were something like a head gasket failing, it may add some pressure within the engine block :noidea: Maybe I can check the spark plugs?

I should mention that the temperature of the sea water itself is around 69-70 F.

 

[MI_Pirate]

I also snaked the intake line through the transom to see if there were anything clogged in that section of the line.

The engine ran a little bit cooler . . . 170 ish vs 175-180 previously, but the starboard engine still runs 155-165.

Just a thought. Pull the water inlet housing off the transom assembly on that port engine. Visually inspect the end of the water inlet hose for corrosion / blockage. I only have 1 engine, but I just fixed this on my boat. I'm not sure what you used to snake that hole, but since you DID manage to change the symptom when you did it, I suspect that you managed to disturb a blockage just enough to get a bit more water flow than it had before. If you remove the pivot pins from the bell housing and remove the U joint bellows from the bell housing, you will have enough access to change it. Merc has a "Design 2" hose with a plastic tube where it goes through the transom that is very easy to install.