Port Engine runs hot on plane

[paboater76]

Hello all,

I'm having an issue with my port engine. I'm running out of options tracking down the root cause of the high temp.

While at idle and up to about 2000ish rpm's the engine will run and stay cool. but start opening up the throttles headed up to cruising speed, as the rpm's increase so does the temp. It gets to about 190, at that point I pull back the gas back to the 2k range and the gauge comes back down to normal levels.

So here is what I have done thus far to correct the issue and I'm running out of idea's

FWC CR270's

Replaced ALL engine hoses with shields 250 series. When I say all, I mean every single hose has been replaced, including the 3" and 4" exhaust and the 3x3x4 tee.

Replaced the risers and elbow up to the manifold, (did not replace manifolds)

Inspected and replaced the raw water impeller. The housing and cam plate look good.

Inspected and replaced the thermostat and housing. Housing looked good, had restriction plate installed

Inspected the oil cooler, all tubes are clear.

Remove the heat exchange and had it cooked, cleaned and pressure tested (all good)

Here are the things we have not looked at or replaced

the engine water pump
the manifolds

How likely is the engine circ pump to go bad? Also manifolds? they only see antifreeze, so they should be good? any suggestions on what to look at next would be greatly appreciated.

I also just completed a port transmission swap, I blew forward gear during a WOT sea trail. Maybe the trans going out was sending to hot of fluid to the trans cooler? causing a loss of cooling to the heat exchanger ? idk, I'm reaching for ideas... but the engine heat issue was there at the end of last season when the trans was running fine.

Thanks,
J

[Viper]

- Do you have the U shaped oil cooler? These are notorious for contributing to cooling issues.
- Have you checked the raw water intake hose from the seacock to the pump?
- Are all the hose clamps tight?
- Are you sure there is no blockage in the intake?
- Are you sure all the air has been burped out of the fresh water cooling system?
- Is the engine timed and tuned properly?
- Are you sure the belt and pump aren't slipping?
- With the heat exchanger cap off and the engine at running temp, do you see any movement in the coolant in the heat exchanger? You can usually see some movement if the circ pump is working.
- Have you confirmed that there is no blockage in the muffler from a broken baffle or something else?
- Have you confirmed with an IR temp probe that the engine is indeed overheating?
- Did you see any wear in the pump body or wear plate?
- Did you try replacing the hose after the pump with a clear one to check for air bubbles?
- I assume the prop isn't fouled?
- I assume the other engine is pulling its load?
- Did you do the work you noted above or a marine mechanic?

In general, FWC manifolds should last a long time but if something prevents them from dissipating heat fast enough, such as a restriction in flow, they can contribute to overheating.

[km1125]

To answer a couple of your questions:

The trans isn't causing it. There's a limit to how much heat the trans can get rid of via the heat exchanger and you're trans would be having more of an issue than the engine if it was generating that much heat

You manifolds should be fine if they've always been FWC.

I would do some IR checks while the engine is under load.

How many hours are on the engine and the raw water pump? Has the raw water pump ever had a major rebuild or had the cam replaced?

[paboater76]

Source of the post - Do you have the U shaped oil cooler? These are notorious for contributing to cooling issues.
- Have you checked the raw water intake hose from the seacock to the pump?
*Yes, new hose was just installed.
- Are all the hose clamps tight?
*Yes, checked and rechecked while running under load
- Are you sure there is no blockage in the intake?
*No not positive, are you talking the eel grass strainer?*The boat was just fully sanded and painted, I checked the intakes he did not paint them, and the tape was removed, I did not however run something up each hole to ensure they were clear. I would need to haul the boat to confirm.
- Are you sure all the air has been burped out of the fresh water cooling system?
*I just swapped a VD trans so system is empty right now. There is no bleed screw on my thermostat housing, so we remove the hoses to insure they fill up from adding coolant into the heat exchanger. Then we check and recheck adding coolant till it wont take anymore, then let it completely cool down, then do that over again.
- Is the engine timed and tuned properly?
*Yes, tuned while under load and on plane.
- Are you sure the belt and pump aren't slipping?
Yes, they look good, no belt burn and they are tight.
- With the heat exchanger cap off and the engine at running temp, do you see any movement in the coolant in the heat exchanger? You can usually see some movement if the circ pump is working.
*Yes, until everything warms up and I need to put the cap on. You can see it flowing by.
- Have you confirmed that there is no blockage in the muffler from a broken baffle or something else?
* No, probably would need to pull the boat to check that, as I would have to disassemble the rear bed and then pull the muffler right at the water line. But the discharge at idle at the dock is the same as the other engine.
- Have you confirmed with an IR temp probe that the engine is indeed overheating?
*No, that is our next step now that the trans is replaced and ready a 2nd attempt at a sea trial.
- Did you see any wear in the pump body or wear plate?
*No, they looked good, not worn or grooves on the housing or the cover plate. Cam plate looked good as well. My Mech took the E35 RWP with him to insall a helicoil for 1 of the cover plate bolts. He is going to compare it with a new cam plate as well.
- Did you try replacing the hose after the pump with a clear one to check for air bubbles?
*No, its that short little almost 90deg hose. But we had it off and it is in good shape.
- I assume the prop isn't fouled?
*No, def not, bottom was just fully sanded and painted, prop shaft is buttery smooth and can be rotated by hand in either direction. Also no change from last year to this year on the temp issue. Boat was OOW for the winter.
- I assume the other engine is pulling its load?
*Yes, runs, great, pulls it load, stay cool on plane 3k rpm's. Timed the same, plumbed the same. They sound the same under load, they are in-sync at the helm etc.
- Did you do the work you noted above or a marine mechanic?
Yes, the lead tech at a well known marina. The bonus is we were friends before he was my mech lol.

That's was he said as well.
In general, FWC manifolds should last a long time but if something prevents them from dissipating heat fast enough, such as a restriction in flow, they can contribute to overheating.

Thanks for the reply, we will check all of those things this weekend.

[paboater76]

O I do not have the U cooler, mine is straight thru, we have it off and you can clearly see through all the holes end to end.

[paboater76]

Source of the post To answer a couple of your questions:

The trans isn't causing it. There's a limit to how much heat the trans can get rid of via the heat exchanger and you're trans would be having more of an issue than the engine if it was generating that much heat

You manifolds should be fine if they've always been FWC.

I would do some IR checks while the engine is under load.

How many hours are on the engine and the raw water pump? Has the raw water pump ever had a major rebuild or had the cam replaced?

Good to know about the trans and manifolds. I bought the boat last year, from the best I can tell about 1000 engine hours. I do not know if the RWP has ever had a major rebuild. Mech currently has it with him. I might just go down and open the seacock lol.

[paboater76]

Well turns out the CAM plate was about half worn compared side by side to a new one. So RWP going back on this weekend followed by another sea trail, pray for good luck!

[km1125]

Well, that does sound promising!! You could do some calcs on how much pumping capacity you'd lose but a sea trial would be more fun!

[paboater76]

If that does not cure the heating problem, I'm going to take the starboard seacock to the port engine and the port seacock to the starboard engine and see if that moves the problem.

[Viper]

Source of the post If that does not cure the heating problem, I'm going to take the starboard seacock to the port engine and the port seacock to the starboard engine and see if that moves the problem.

Source of the post

Source of the post....Have you confirmed that there is no blockage in the muffler from a broken baffle or something else?
* No, ....But the discharge at idle at the dock is the same as the other engine....

If this is your answer to my question above, why would you suspect a restriction anywhere else? Before you swap seacock lines, close both seacocks, remove the lines, then open the suspect seacock and closely observe flow. Don't worry, it won't be a torrential flow. Then shut it off, then do the same to the other side and compare the flow.

If you remain in the water during winter and the water freezes, it could affect the seacock. Can you open and close the seacock easily?

Source of the post

Source of the post.... Have you confirmed with an IR temp probe that the engine is indeed overheating?
*No, that is our next step now that the trans is replaced and ready a 2nd attempt at a sea trial....

Did you do this yet?

The question about replacing the outlet hose with a clear one wasn't intended to determine the condition of the hose, it's a trick used to check if you're getting air in the flow from anywhere in the system including a cavitating pump.