Perkins 4.236 running hot

[Gulfstar 36]

We just got back from a 3 day cruise and my stbd engine was running hot. We normally run about 1900RPM but the stbd engine now at this temp seems to over heat. The gauge was over 200 before I noticed it and backed off on the RPMS. Running at 1600 the temp maintains 180. The port engine never goes higher than 170 at any RPM. Once we arrived I noticed green AF in the bilge but the only way that could have gotten there was from the overflow at the fill cap. I added about 3 quarts to the port engine. Both engines appear to have the same water flow from the exhaust.

Where should I start?

Thanks

 

[Gulfstar 36]

I meant to say added 3 quarts to the Stbd engine.

 

[FlyWright]

Has anything else changed recently on the stbd engine? Recent maintenance?

I'd start with the raw water pump impeller inspection/replacement. Any missing blades? Any lost pieces impeding flow downstream? If that's all good, how's the coolant pump?

If you can place a small container under the coolant overflow line, you can verify if that's the source of coolant in the bilge and not a failed hose or radiator cap.

 

[Pineapple Girl]

This happened to a friend and he'd sucked a bunch of plant life in that was clogging his intake. He found that AFTER he changed the impeller to no avail.

 

[JAT]

When was the last time you cleaned the heat exchanger? You could have a problem there. If the water flow is restricted...she'll heat up at higher RPM's.

Defective thermostat? As in not opening properly.

I don't know that much about the 4.236, my engines are 6.354's, and the only other item I can think of engine wise would be a restriction in the oil/raw water cooler a part that might look like this if you have them. Sen-Dure - PERKINS Oil Coolers

 

[driller66]

perkins 6 cylinder

Hi folks!! I've actually got a question about my Perkins 6 cyl. that I'd appreciate your feedback and ideas on . Starts up in the morning cold and idles nicely at 600-700 RPM, after 15 or twenty minutes when she's warm the idles up to 1000 and never goes down below. I'm suspecting the injector pump. Any ideas or other suggestions? Many thanks in Advance for your time, experience and wisdom!!
Peace

 

[sunchaser]

Starts up in the morning cold and idles nicely at 600-700 RPM, after 15 or twenty minutes Peace

Why do you idle so long?

 

[Gulfstar 36]

I guess the best thing for me to do would be to try to wrestle the heat exchanger off and ether clean it or replace it. The engine is 38 years old and I'm sure that are not in the best shape. It is just that this one is on the hull side of the engine and a real bear to get to. Does anyone know if the exhaust manifold has to come off? Also how hard is it to get to the thermostat?

Thanks

 

[RickB]

I guess the best thing for me to do would be to try to wrestle the heat exchanger off and ether clean it or replace it.

Before you literally open a can of worms, circulate a cleaning medium through the raw water side and see what that does.

There are plenty of web posts showing how to do it yourself and if you are not so inclined, find a fellow boater who can help. It isn't too difficult - it's much easier and less risky than wrestling parts off on spec.

 

[Gulfstar 36]

Something like method 2 in this post? It looks like my flow goes like this. Raw water pump > Oil cooler > Heat exchanger > Exhaust manifold > Mixing elbow. I assume this mixture is OK for all parts in this path?


How to Service Your Yacht's Cooling System

Before you literally open a can of worms, circulate a cleaning medium through the raw water side and see what that does.

There are plenty of web posts showing how to do it yourself and if you are not so inclined, find a fellow boater who can help. It isn't too difficult - it's much easier and less risky than wrestling parts off on spec.

 

[FF]

I would start with closing the seacock , pulling the hose and opening the seacock.

LOTS!!?? of water continue the process thru the engine .

 

[2DASEA]

I would pull exchanger, should be done regularly for cleaning and inspecting. A good radiator shop can help. !'ve pulled lots of old impeller pieces out of heat exchangers.

 

[2DASEA]

Another idea, check elbow in cooling loop they get corrosion that closes them up and restricts flow....

 

[Gulfstar 36]

Thanks! This is the hard one to get to, so I'm going to try a few in place fixes first then remove it for replacement or cleaning during the off season.

 

[JAT]

Hi folks!! I've actually got a question about my Perkins 6 cyl. that I'd appreciate your feedback and ideas on . Starts up in the morning cold and idles nicely at 600-700 RPM, after 15 or twenty minutes when she's warm the idles up to 1000 and never goes down below. I'm suspecting the injector pump. Any ideas or other suggestions? Many thanks in Advance for your time, experience and wisdom!!
Peace

My 6.354's after warming up...do the same thing. I do believe its art of the "anti-stall" mechanism...or something like that. I generally idle my engines for only a few minutes before using the engines. But I do not think there is anything wrong with the injector pump. I have two 6.354's....and they both do it.

 

[Gulfstar 36]

So I'm running out of options. Impeller looks OK, I flushed the HE with acid but still getting hot. I'm thinking may a stuck thermostat. I'm getting good flow out the exhaust. But I noticed the fresh water tank gets hot but the raw water line that goes to the mixing elbow does not. this would seem to be a lack of exchanged heat. I assume that if the thermostat was stuck shut fresh water would never reach the heat exchanger? Who knows where the thermostat is on a Perkins 4.236?

 

[rochepoint]

Google is your friend, I found this shop manual on the net at:
http://igor.chudov.com/manuals/Perkins-Diesels/Perkins-4.326-Diesel-Engine/Perkins-4.326-Workshop-Manual.pdf

It is a big 8.4 meg download so it will be a little slow downloading but should help.........

 

[Gulfstar 36]

Not a very good document for the M series engines. I suspect it is under the coolant tank. I do have a hard copy of the workshop manual for the 4.236M but it does not identify it's location. I head over there in a little while and scope it out.

Google is your friend, I found this shop manual on the net at:
http://igor.chudov.com/manuals/Perk...esel-Engine/Perkins-4.326-Workshop-Manual.pdf

It is a big 8.4 meg download so it will be a little slow downloading but should help.........

 

[Gulfstar 36]

Well I finally got out today for a few hours. The temp never went over 180 after an hour at 1900 where I normally run. I think it might have been the second muriatic acid flush after the phosphoric one. I did also see a kink in the exhaust hose that I straightened out somewhat.

 

[expat]

great

 

[Gulf Comanche]

Two things you might look at:
1. The top hose coming off the heat exchanger going to the mixer, take it loose on the exchanger end and see if it is clogged, you will need a new gasket when you put it back on. The hole is small and was clogged when I rebuilt my cooling system on the 4-236. Of course, it was the last thing I found & repaired at the time.
2. The mixer: mine was shot so I replaced it with a new one, really helped, no more steam or overheat issues.
Both of the above are fairly easy to do compared to rebuilding the whole system, and I have a fair amount of room to work on mine.
Mike

 

[Astral Blue]

These engines are notorious for getting pockets of air trapped in the cooling loop. In many cases, bleeder valves are placed on the manifold (the highest point on the cooling system) to evacuate the air.

Chances are there was some air trapped in your system and it burped, popping your reservoir cap and spilling coolant.

Depending on the type of manifold you have on your engine, there is most likely a brass plug somewhere along the top surface. When your engine is cool, remove the plug and check to see if you have coolant. If you don't, there is most likely air trapped there. Leave the plug open and begin filling your expansion tank. Once the coolant level reaches the top of the plug (not the expansion tank), stop filling.

You want to make sure there is no air in your cooling loop. These engines do evacuate the air rather well, but it often results in a nasty burp similar to what you experienced.

Also, give your engine a cold start with the tank to your expansion cap open. If you see bubbles coming out if it, let us know. The problem then becomes more serious and lies outside of trapped air.