Indmar 340 cat

[docdrs]

For all those that have the cat 340 engine, I just talked with Larry at Indmar about a engine temp problem I have been experiencing. Occasionally at idle my temp would spike up to 170, 180 and this past weekend 203 setting an engine fault code. I check my screens Water filter, and trans cooler all were clear. check my impeller previous and was fine , but decided to replace it ...the one i pulled out looked brand new but replaced anyways...(took 30 mins on my v drive silicone lube and large needle nose vise gips and back panel remover for easier access.
Anyways Larry explained that at lower rpm with the cat running so hot that the water vapourizes to steam in the jacket and enters the top of the water distribution and then the J tube gets sucked shut from the water pump sucking causing a popping sound of the tube compressing and expanding. Giving a little throttle in gear or neutral will increase impeller flow to cool the cat and stop steam.......an fyi for cat owners and thanks for the explanation Larry

[KG's Supra24]

Thanks for the heads up docdrs. Is it possible to give it gas/throttle while in neutral?

[docdrs]

yes you can push in the tranny release and do it in neutral

[jzelt]

Bottom of the throttle lever, there is a button (where it hinges, you push that in). Disengages the transmission.

[tg0824SSVGG]

Wonder if this is what caused my "Engine Fault" this weekend. Boat going later today for a reading.

[tg0824SSVGG]

But the acceleration won't clear the code ... and once it happens, on my boat at least, you can't turn off the perfect pass, or even change the speed - it's STUCK ON

[docdrs]

turning my engine off, then on again cleared the code, but then i shut the engine off right away when i saw the code.......prob was not the best thing to do as discussed with Larry as maybe should have revved the engine, to cool it down, but i started it right back up and the code was cleared and engine cooled right down.....I did not have PP on at the time. wonder if you disconnect all power for 5 mins then reconnect if it would clear your code?? look on the Indmar website the have a service tech at your whim....... 1-800-238-7112

[Fman]

For all those that have the cat 340 engine, I just talked with Larry at Indmar about a engine temp problem I have been experiencing. Occasionally at idle my temp would spike up to 170, 180 and this past weekend 203 setting an engine fault code. I check my screens Water filter, and trans cooler all were clear. check my impeller previous and was fine , but decided to replace it ...the one i pulled out looked brand new but replaced anyways...(took 30 mins on my v drive silicone lube and large needle nose vise gips and back panel remover for easier access.
Anyways Larry explained that at lower rpm with the cat running so hot that the water vapourizes to steam in the jacket and enters the top of the water distribution and then the J tube gets sucked shut from the water pump sucking causing a popping sound of the tube compressing and expanding. Giving a little throttle in gear or neutral will increase impeller flow to cool the cat and stop steam.......an fyi for cat owners and thanks for the explanation Larry

Doc,

How often does this happen to you? Knock on wood, but I have never been above 165 degrees, even on the hottest day. I do run my blower all the time to circulate cooler air in the engine compartment. Does idling in nuetral cause this to happen? Also, how did you check your trans cooler for blockage?

[docdrs]

this condition only happens when i am idling after the engine is warmed up.....it has only happened about 3 or 4 times in about 60 hours of operation....but i have been watching my temp closely and usu its sits between 159 and 162......when i idle it for a longer period of time is when i notice a temp fluctuation usu it does not go above 169......sometimes 177.........but it can rise quite fast as i believe the steam is entering the system and the cause for the temp spike.....not a tru engine overheating...... with the cat running between 800 and 1200 degrees you can see how quickly the water can boil in the exhaust mani creating the steam.......steam rises and thus will come out the top manifold hose into the circulating system due to the increase steam pressure.......as i understand it........when i am running any speed at all i have no temp increases.....maybe the temp sensor is close to the block intake?

[SupraTamu]

This helps explain what happened to me a few weeks ago. We were out wake boarding then came in at idle to a cove and then my temp went up and gave a warning but no code came on and we got out of the no wake area and sped up and the engine cooled down immediately. It all is making sense now.