Closed Cooling System on Port Engine Running Hot(ter)

[tpenfield]

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.

Thanks for the input. I may try to snake the inlet tube again. My challenge is that the boat, being a 33 footer, is a bit costly ($660) to take out of the water and re-launch. So, most of my 'in-season' maintenance is done with the boat in the water. I had the outdrive off over the winter and I don't recall seeing any marine life in the outdrive water duct or inlet tube at the bell housing. However, it is possible that a barnacle grew inside the outdrive water inlets and is now dislodged and working its way up the inlet tube as the sea water pump tries to suck in water.

 

[tpenfield]

Sunday Update:

I snaked and flushed the intake line that comes through the transom again . . . not any difference.

I partially blocked the water outlet leading to the elbows on the starbd engine to see how that engine acted with reduced flow. . . it pretty much raised everything a few degrees, so not any sort of correlation that I could tell.

Then I checked the oil . . . golden brown.

I also inspected the engine for signs of antifreeze seeping out from the head gasket areas. Nothing that I could see.

I did not have time to do much more with the boat. We did take the boat out today and it seems to run as it did yesterday. It does like being at the higher RPM's versus idle speed It will heat to 165 F at idle, whereas the starbd engine will be at 145 F, but at 3200 rpm (40 ish mph) the port engine will be 170-172 F and the starbd engine will be 160-165 F.

It could be a head gasket starting to go, but that will require some more diagnostics. My plan is to keep an eye on it and do a few more tests as I have time.

 

[tpenfield]

Doing a bit of research last night, I found that there are some 'test kits' available that can determine if exhaust gases are escaping into the coolant, which would indicate a head gasket failure. So, I may try one of these to determine if the issue is a head gasket problem.

 

[tpenfield]

OK, another weekend coming up, so another run at the port engine cooling issue. . .

I got myself one of those Lisle test kits that determines if exhaust gas is getting into the cooling system.

I have my timing light, as Chris had asked about the ignition timing earlier. So, I'll check that.

I have my inspection camera all charged up and ready to go, just to see if I can find any signs of coolant around the head gaskets.

I'll probably check the spark plugs . . . been meaning to do that.

I am also going to try to see if I can get a decent temp reading with the IR Gun on both cylinder heads to see if the issue is on one side of the engine . My initial temperature reading was after the coolant flow had joined back together at the thermostat housing.

Overall, the boat is still usable, since the port engine does not over heat . . . just runs 15 degrees hotter than the starboard engine.

 

[mr300z87]

Hi Ted, Been following along on this have read your other threads I also love your Formula, there is a deal near me and there are a lot of them on Barnegat Bay where we boat. First let me say that I am in the IT business and am not an expert mechanic, just a guy that likes playing with engines. One more thing I thought of was, could the engine that is running hot have an issue with something that is causing a lean condition hence only slightly hotter than normal. Good Luck

Mike

 

[alldodge]

I don't think your moving enough water, if that is the pump or a restriction don't not right now. Water coming in is the same, it goes thru the cooler, heat increases. I see D as coming out of the HE, and this is where the temp jumps up. The heat change from then on is about the same as the starboard motor.



So the issue is how to find out where the restriction is. Suggest getting some clear hose and install somewhere after the seawater pump and before the HE. Would be great if we could also see pressure but I'm thinking your sucking air

 

[tpenfield]

AD, actually you have not marked the temps correctly. I did post a second spreadsheet, where I did all the calculations (yellow highlighted numbers)

The sea water as it is going through the HE is starting at 78 degrees "A" ( after the oil coolers) and goes up to the 93-94 range for the starbd engine and 97-98 range for the port engine, which are the "B" figures.. The very hot temps are the coolant temps on the closed side of the system.

"D" is the coolant as it has comes out of the exhaust manifolds and joined at the fitting heading into the HE. "C" is the coolant coming out of the HE and headed back through the engine to get some more heat.

The heat exchangers are taking a lot of heat out of the coolant, and actually the port engine HE is taking more heat out of the coolant (-87 F) than the starbd engine HE (-70 F). So, it still is a bit baffling at this point.

 

[tpenfield]

Hi Ted, Been following along on this have read your other threads I also love your Formula, there is a deal near me and there are a lot of them on Barnegat Bay where we boat. First let me say that I am in the IT business and am not an expert mechanic, just a guy that likes playing with engines. One more thing I thought of was, could the engine that is running hot have an issue with something that is causing a lean condition hence only slightly hotter than normal. Good Luck

Mike

I looked at a 1999 Formula 280SS on Barnegat Bay back in 2012, made an offer, but did not come to terms. I am in the I.T. business too, but I tend to get dirt under my finger nails, as you do.

I will see if the spark plugs look like a lean condition. aChris thought the timing may be an issue as well.

 

[tpenfield]

Here are my numbers from last week with a bit more annotation. I *think* the problem is where I circled in Red . . . :noidea:

It looks like both H.E.'s are taking a lot of heat out of the coolant, bringing the coolant down to the same temperature as the exiting sea water, so it could not take any more heat out than it is already doing.

 

[alldodge]

I'm sure your right but sure had a hard time trying to use your drawing and matching it to the actual closed cooling layout in manual 16. I see the labels, look at your actual pics, but it does not add up to what I see in the manual, nor what I've rebuilt. Either way just my take

 

[tpenfield]

Yea, by drawing wasn't too good. I was thinking that I should have drawn some flow lines . . .

It is an aftermarket cooling system, so may not be 100% of what is in the manual.

 

[tpenfield]

Sea water goes A -> thru H.E.-> B -> E/F

Coolant goes C -> H/J -> thru Engine Block -> L/N -> thru Exhaust -> K/M -> D . . . then thru the H.E. and back to C

 

[tpenfield]

AD - I found some better diagrams and put the temps on them. Hopefully, these will be more clear. All ideas welcome . . .

First the starboard engine:


.
.
.
Here is the Port Engine:



It seems like the source of the temperature rise is in the engine block/heads as the temp rise through the exhaust is just about the same for each engine, and the port engine is cooling the hotter coolant down almost down to what the starboard engine temp at that same point is (93 starbd vs 98 port) whereas the coolant goes into the HE at 163 starbd vs. 185 port.

 

[alldodge]

Those help me a bunch, thanks
Agree, heat rise is happening in the motor, now to find out if its a malfunction or restriction of flow. Hope the plugs will show something, maybe a lean condition.

 

[tpenfield]

Quick update:

Timing checks out OK. The exhaust gas test was negative so no exhaust gas in the coolant . Admiral and crew showed up at the dock with a cooler of beer. So, I did not pull the spark plugs today.

 

[mr300z87]

I agree with you and AD that the issue is with engine and think AD and I are onto something with it being lean!! A lean engine will definitely run a little hotter like you are experiencing. Since I not familiar with the MPI system on you have I will leave diagnosing it to others. I working on a project with similar vintage 7.4 L but it is a carb'ed engine.

Enjoy those beers with the family, we are headed out later for a dinner cruise once all the crazies are off the water.

 

[tpenfield]

Thanks guys, I'll be checking the plugs tomorrow for signs of a lean condition. The engines have the MEFI1 controllers, which are the first generation of engine controllers. If it is running lean, would I assume that the injectors are either clogged or getting tired . . . :noidea:

Just for kicks . . . I switched radiator caps on the engines when I was doing the tests this morning . . . of course I would have fudged my shorts if it made a difference . . . didn't

 

[tpenfield]

I agree with you and AD that the issue is with engine and think AD and I are onto something with it being lean!! A lean engine will definitely run a little hotter like you are experiencing. Since I not familiar with the MPI system on you have I will leave diagnosing it to others. I'm working on a project with similar vintage 7.4 L but it is a carb'ed engine.

Enjoy those beers with the family, we are headed out later for a dinner cruise once all the crazies are off the water.

I remember seeing your project thread a while back. :thumb:

Anyway, I am glad that the combustion gas test was negative, as It would not be fun taking the 7.4L apart. I did that on my previous boat, but it was so much easier, being a smaller boat.

Using the IR Temp gun has really helped on this diagnostic challenge. I figured that the heat exchangers were working OK, since the ratio of 'temp drop' to 'temp rise' between the two engines were nearly identical:

Port Engine H.E. -> (185-98)/(97-78) = 4.58

Starbd Engine H.E. -> (163-93)/(93-78) = 4.66

I think that is also indicative of the sea water flow also being fairly equal between the two engines.

We did some tubing yesterday and when I shut the engines off while boarding the tubers, the port engine would spike up to 190 ish. I don't ever recall seeing 190 on those engines. I think the temp alarm will sound at about 200 F. :noidea:

 

[NHGuy]

Ted, I hadn't been following your thread but just gave it a first read. I didn't see where you did a swap of the 2 heat exchangers. If that was done and the clear tube test shows no air, AND the heat stayed with the same engine I'd then rig a 1970's - 1980's auto cooling system backflush.
In those setups a backyard hose sized port is added to an automobile heater hose.
But you can be more precise.
First remove and backflush the coolant side of the HE in case it has debris in it. Then run the engine and see what it does. That's the equivalent of flushing some automotive heater cores.
If it's still too warm you could backflush the antifreeze system.
Remove the thermostat and reinstall the thermostat housing empty. Remove the water pump belt, so it is free to turn backwards. You are rigging it so the closed system liquid flows backwards. You may end up removing the hose at your seawater pump and connecting a temporary line overboard- I would do that in case the seawater pump cannot tolerate backflows. If that seapump is designed as I think raw water would flow in at all times. So if you have a through hull turn off it would need to be closed. If not, we can't sink the boat so that needs a good sealing clamp, plug or cap.
Here's where you make some choices. If you have water available at the dock, flush it there. If you don't you could tee off the other engine and use it's raw side to pump the seawater through your hot block backwards! Or to avoid messing with the good engine perhaps you could use a separate water pump that runs off electricity, AC at the dock or DC on the mooring... Or AC on the mooring, I forget that those bigger boats have AC aboard!
With line clamps you can isolate one side at a time so if there is a restricting piece in one side it won't just force the water to go the other way.
If you want to know what comes out you'd need to put a good sized screen bag on the outlet to catch anything that is expelled.
I suppose you can also remove the water recirculating pump and rod out the block while it's off. You really can't reach all the way in but I'd have an assortment of long brushes and coat hangars on hand for that adventure.
If you go that route you risk freeing up more scale that could mess up things further in the closed system. But if there's stuff in there it may get free sometime, so perhaps it's something to do and be certain of. If you do that you'd be smart to do it BEFORE the block flush.

Hope this helps, check my logic.
Maybe someone else knows more and can tweak the process I laid out.

 

[tpenfield]

Thanks, NH for the advice.

BTW - I bought this boat at Meredith Marina back in 2012. My first time being on Winni. The boat was purchased at Lakeport landing in 1996 and had 3 owners on Winni before I bought it.

I did not swap the heat exchangers, but did both a coolant side back flush (HE only) and the sea water side backflush and de-scaling.

I had thought about doing a coolant system backflush, but haven't really taken it to task.

A bit of history on the issue is that the port engine started to run a bit hot (165-170) last year. I flushed the seawater intake, etc and it got a little bit better. This year it started out worse than last year (170+) and proceeded to get worse after the first few runs of the season(175-180). The work that I have done so far has made another small improvement from the worsened condition (170).

Current theories are:

- Lean fuel mixture condition

- Recirculating pump problem

- Some sort of obstruction in the cooling system

My thoughts on getting into the engine block (if necessary) would be to take off the exhaust manifolds and pop the core plugs and flush any sediment out.

I'm going to check the spark plugs for signs of a lean condition this AM and I did by a new timing light to re-check the timing, as my old timing light was a bit iffy.