Indmar 340 cat

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 :)

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

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

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

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

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

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

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Originally Posted by 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 :)

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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?

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?

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.

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Originally Posted by 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 :)

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I had the same problem except I had a bad thermostat that had to be replaced. I do notice that at idle the motor runs a little hotter than normal but as soon as you put it in gear and get some water flowing it is fine. Scary experience nonetheless.

Wow. Now there is a workaround but this is scary. As far as I know 200 is the temp where head gaskets start blowing. This is clearly a design flaw and I hope they come up with a fix and issue a recall. Who ever heard of a boat where you can't idle after the engine is hot. I have yet to see this issue in 30 hours and hopefully will not. Scary.

I hope there is not a defect with the 340 I am on my second engine on a new 09 22ssv. first engine bent several pushrods at 30 hrs but never ran hot. Indmar made me wait 5 weeks for a new engine and ended up putting a new 2011 in the boat. wouldn't say why they made me wait for the new production run. wish me luck :mrgreen:

Does anyone have an update on whether Indmar has come out with anything that can be done, to fix this issue, rather than requiring the workaround?

I only ask because we blew one engine while my wife was driving (damn pine needles clogged the impeller -- by the time she realized the temp was rising, she turned it off and it was too late) -- now the wife is very weary of driving the boat. We just replaced that boat (a Moomba) with our new Supra, which has the 340 CAT, and I'm worried that the wife is going to have another tramatic experience if I don't address this prior :-)

Thank you in advance!

I have 2 boats with the 340 cat engine in them. One 2010 in Saetta Classic with 78 hrs on it, one 2011 in a Supra launch 242 with 182 hrs on it. Never had this problem with either engine. A friend with the same engine had a similar overheat at low speed which turned out to be an impeller that needed replacement which fixed the problem. I did update my 2010 engine (2011 engine has it from new) with a modification to the thermostat housing suggested by Indmar to prevent steam build up and lack of water flow in the cat manifolds. I learned of this in December when I was at Indmar for engine training but I do think info on this mod is available to dealers as well.

Since this post I have had the new thermostat housing (a small hole drilled thu it) and brass fittings rather than plastic placed on the top cat cooling supply fittings.

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a modification to the thermostat housing suggested by Indmar to prevent steam build up and lack of water flow in the cat manifolds.

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Kjkimball & Docdrs - thanks a lot for this!

Is this something I can retrofit by removing the assembly and drilling a hole somewhere, or do I need to buy a new pump assembly? If the only option is the new pump assembly, would you go thrugh SC or Indmar?

Thanks again for your insight!
-RKM

It is a mod to the thermostat housing not the pump. It is a simple thing to do and Indmar has the data. I you decide to do it, you will need the info from Indmar, thermostat gasket, sealer, and get a thermostat and change it while you are there. Te easier way would be for you to contact Indmar service with your engine serial number and get the proper parts from them. Ask for the price on a new modified housing too and that may be low enough for yto just buy it and swap yours out instead of drilling the old one.

As I wrote before, i have one that was this way from the factory and one a year older that was not. Never had a problem with the older one but upgraded it with new parts anyway.

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Originally Posted by kjkimball

It is a mod to the thermostat housing not the pump. It is a simple thing to do and Indmar has the data. I you decide to do it, you will need the info from Indmar, thermostat gasket, sealer, and get a thermostat and change it while you are there. Te easier way would be for you to contact Indmar service with your engine serial number and get the proper parts from them. Ask for the price on a new modified housing too and that may be low enough for yto just buy it and swap yours out instead of drilling the old one.

As I wrote before, i have one that was this way from the factory and one a year older that was not. Never had a problem with the older one but upgraded it with new parts anyway.

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I agree with above. You have to remove intake cover 6 allen bolts slightly to get at tstat housing bolts unless you have universal joint shallow sockets. Its a simple 20 min job. I should have taken a pic last time I had mine off

I can't thank you guys enough for the heads-up as well as the assist on this.

I'm calling Indmar first thing tomorrow and ordering the parts/instructions.

Once I get them I'll scan/post here, for others.

Thanks again,
-RKM