Closed Cooling System on Port Engine Running Hot(ter)

[tpenfield]

UPDATE:

I found something when I took the outdrive off . . .



That turned out to be a sea shell that apparently grew inside the outdrive water duct and then dislodged and got stuck that the fitting for the intake tube. Not 100% sure this was the source of that problem, but it does fit the symptoms.

I'll be running the engines today with a hose adapter into the bell housing. If I get favorable and comparable ECT results between the two engines, then it might be case closed for this.

I had a similar problem on the F-242 . . . a whole barnacle grew inside the outdrive duct and dislodged, ending up in pretty much the same place. The only difference was that being a complete barnacle, it restricted the flow even more than what this sea shell appears to have done.

 

[alldodge]

Some times ya find the strangest things

 

[tpenfield]

Some times ya find the strangest things

Sure do . . .

So I ran the engines up to temperature . . . took about 20 minutes to come up to temperature and stay steady

Here is where the Port engine ended up



Here is where the Starboard engine ended up.


Keep in mind that the Starboard engine has 2 small holes in the t-stat flange for by-pass and the Port engine has 3 small holes for by-pass. I guess that one additional hole (1/8" dia.) makes a difference.

Anyway, I'm good with this. :thumb: If anything the Port engine will be the cooler one

Stupid sea shell . . .

As an added precaution for next year I will make sure the intake duct within the outdrives are clear and coat the insides with anti-fouling paint. I try to do that every couple of years, but will make it an annual thing going forward.

 

[JASinIL2006]

Four hundred some posts over 27 pages... some of the most interesting detective/diagnostic stuff I've read on iboats... and it was a shell. Wow!

 

[GA_Boater]

Stupid sea shell . . .

I hope you framed it and have it hanging on a cabin bulkhead?

 

[tpenfield]

Four hundred some posts over 27 pages... some of the most interesting detective/diagnostic stuff I've read on iboats... and it was a shell. Wow!

I hope you framed it and have it hanging on a cabin bulkhead?

I think it was Rick who said it was bound to be something simple . . .

. . . and here it is.



I showed it to the Admiral and she just said . . . "that little thing caused all those problems ??? "

Yup

 

[GA_Boater]

On the good side;

Rust flush
New thermostat
Diacom history for the future
A whole bunch of other stuff scattered throughout the 28 pages and 400+ posts.


#1 - You found the cause. :thumb:

 

[tpenfield]

I am thinking what happened is that the shell grew inside that outdrive last year and died/detached over the winter. This year upon launching and the engine running at speed, the shell probably followed the water flow right up to the bell housing where it lodged at the insert fitting.

 

[alldodge]

I am thinking what happened is that the shell grew inside that outdrive last year and died/detached over the winter. This year upon launching and the engine running at speed, the shell probably followed the water flow right up to the bell housing where it lodged at the insert fitting.

Imagine what would happen if the shell made it to the impeller

 

[HT32BSX115]

I think it was Rick who said it was bound to be something simple . . .

. . . and here it is.


I showed it to the Admiral and she just said . . . "that little thing caused all those problems ??? "

Yup

Woohoo!!

Can't remember what I said! But I always thought it would be some sort of raw water obstruction!

That's a pretty good obstruction!! Glad you found it!!:thumb::thumb::thumb:

 

[Lou C]

Wow glad you found it. I had a similar thing a few years back with barnacles growing on the water screen that OMC used to put in the Cobra lower units (same as the John/Rude OB lower units). I tried everything but this, and in the end what solved it, was splitting the drive, removing the water passage cover, cleaning out the water intake area and painting it with anti fouling paints. Inboards have the same issue that's why some use those water intake scoops that can be opened and cleaned out. I wound up taking out the screen and not replacing it. Cools just fine.

 

[tpenfield]

I just did a quick review of this thread and all the 'places' that it went . .

Summarizing, it looks like many aspect of the engines were reviewed . . .

Initial symptoms were port engine suddenly running about 15 degrees hotter than it had run previously. Here is the progression of diagnosis:

1- Impellers were new on both engines
2- Exhaust Elbows then checked
3- Heat exchanger checked, lots of scaling/clogs. descaled the H.E
4- Replace T-stat
5- Swapped the gauges at the helm
6- Used IR Temp gun to verify temperature throughout both engines. - this is where the data seemed to point at the engine block itself as the culprit, which turned out to be wrong.
7- Head Gasket test using combustion gas test kit
8- Look at spark plugs - appeared to be a lean mixture
9- Checked fuel pressure - Starboard was in spec, Port was a bit low
10- Get DiaCom software to check for codes and review engine parameters
11- Replaced IAC
12- New distributor cap and rotor (just for good measure, and they looked a bit worn)
13- Checked timing - spot on.
14- Swapped MEFI's
15- Replaced Fuel Pressure regulator (always buy OEM)
16- Checked recirculating pump
17- Tested raw water flow - starboard engine was about 20% higher flow than the port engine - this was the first piece of data that started to point to the raw water side and away from the engine itself.
18- Checked for Bravoitis - its is in the early stages.
19- Iron flush - lots of iron came out of the engine blocks.
20- Replaced t-stat on Starboard engine and cleaned heat exchanger - make the engine cooling and idle temp substantially the same between the engines
21- Noticed ECT temp is about 10-15 degrees F lower than the gauges (maybe Euro vs USA sender resistance ranges - may do some resistance range checking later on)
22- Ran a compression test - as part of annual check-up, not related to cooling issues
23- Removed outdrive for end of season layup . . . Oh Look . . . A SHELL ?!?!? :facepalm: :facepalm: :facepalm:

 

[Lou C]

And in the end, we come to a shell, which as some of us pointed out way back in the beginning is one of the inherent advantages of outboards in salt water, they tilt up, so nasty stuff does not grow outside, or INSIDE! lol. It took me a little while to rig up a way to separate an upper and lower drive that did not want to come apart, but using some all thread, 1/2" bolts, and 3 scissor jacks, it 'cooperated'. That allowed me to do what I had to do, pop off the water passage cover and clean it out. Good maintenance practice for salt water slipped or moored boats at least every 3 seasons or so.

 

[tpenfield]

Looks like quite an undertaking, Lou. I am hoping that I can just do some sort of roter-router routine with a wire brush on some flex tubing. Then, spray or pour AF paint into the duct.

Usually each year there are some barnacles that grow immediately inside the inlet holes on the lower unit. I usually can crunch them up with a small screw driver. Anything that grows a bit further up the outdrive is not as easily reachable.

 

[Lou C]

Like a lot of jobs, once you've done it, you know the tricks. A good thing about learning how to do this is you remove the bolts every 3 seasons or so and then do not get frozen in place. My OMC mechanic said he does this on all the drives he maintains every 3 seasons or so. Not only do they grow in the holes, but they will grow up in that passage as well. The Cobra has 4 large holes on each side, vs Merc and Volvo use more but smaller holes. Since I left the screen out, I can work a stiff wire bent at a 90* angle up there and clean it out pretty well. It is still a good idea to split the drive every so often. I posted the pix to show people how to do it, not prying on the weak alu casting but using the strongest part of the drive to apply force to (the rear trim ram mounts, and the front mounts).

 

[tpenfield]

A side note, which may be of interest to achris about the Master/Slave setup of the MEFI's on the engines and the DiaCom software. Throughout this thread, I was having some problems with the Port Engine MEFI being 'seen' by the DiaCom Software.

During this latest round of tests, The port engine would barely 'connect' to the software, and when it did it only continued to feed data for a minute or so. Then, I thought about the master/slave configuration that we reviewed . . . I tried turning on the ignition for the Starboard engine (master) while I was running and testing the Port engine, and that instantly resolved the connectivity problem. The software would then ask me which engine and which testing mode, and worked flawlessly. Previously I had been turning on the ignition for just the one engine that I was testing. Seems like it always wants the Starboard engine to be on, even if testing the port engine. . . . probably because it is wired up as the 'master'.

Of course, I am not that keen on just leaving the ignition on while the engine is not running, but for the 5-10 minutes of testing, it seemed OK.

 

[achris]

A side note, which may be of interest to achris about the Master/Slave setup of the MEFI's on the engines and the DiaCom software. Throughout this thread, I was having some problems with the Port Engine MEFI being 'seen' by the DiaCom Software.

During this latest round of tests, The port engine would barely 'connect' to the software, and when it did it only continued to feed data for a minute or so. Then, I thought about the master/slave configuration that we reviewed . . . I tried turning on the ignition for the Starboard engine (master) while I was running and testing the Port engine, and that instantly resolved the connectivity problem. The software would then ask me which engine and which testing mode, and worked flawlessly. Previously I had been turning on the ignition for just the one engine that I was testing. Seems like it always wants the Starboard engine to be on, even if testing the port engine. . . . probably because it is wired up as the 'master'.

Of course, I am not that keen on just leaving the ignition on while the engine is not running, but for the 5-10 minutes of testing, it seemed OK.

:first:

 

[cdiamond]

A CASE STUDY OF

" CHECK THE BASICS - FIRST "

my younger brother was a mechanic long before me

he told me one time - and i never forgot

" Look for the simplest solution FIRST "

 

[achris]

Yep, I was taught it as the 'kiss' principle. Keep It Simple, Stupid.

 

[tpenfield]

Yes, we now have a revised list of basics. . .

1) impeller
2) thermostat
3) sea shell