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johnboat
08-27-2013, 12:11 PM
Hello-
I have a quirky issue with my engine that came up recently and would appreciate any comments on it.

While pulling a slalom skier at 3000 rpm the engine temp spikes up to around 200 degrees and the engine control shuts the throttle off. At the same time, I can drive without a skier at the same rpm without issues. Also I was pulling wakeboarders/trick at 2000 rpm range for hours without an issue. At first I thought that weeds had clogged up the intake or the impeller at intake was shot but all looked good. I have read about thermostat chang outs, or pieces of junk in the tstat, and oil cooler lines plugged. Thus I am prepared to check those things but any other thoughts given the lower rpm's and no issues?
Thanks!

Ski-me
08-27-2013, 12:21 PM
Check to be sure you have the correct thermostats in there. You should have a 160 degree stat (with a small hole drilled on the top) and also a 142 stat (by water pump). Also, check your impellar and install a new one for good measure, if you haven't done it recently.

mikeg205
08-27-2013, 12:30 PM
Darn that LT1 engine at times... DO those steam tubes ever need to be checked to make sure they are clear?

Jerseydave
08-27-2013, 05:09 PM
Darn that LT1 engine at times... DO those steam tubes ever need to be checked to make sure they are clear?

Steam tube at the rear of the engine should be removed (on direct drive boats) and plug those holes. Remove the plugs at the front of the heads and install brass fittings/hoses. There is a thread on here somewhere regarding the fix (mastercraft had a bulletin for this)

And yes the steam tubes can clog with sediment.....mine were, then they started to leak water because they were rusted through.

Jerseydave
08-27-2013, 05:11 PM
Hello-
I have a quirky issue with my engine that came up recently and would appreciate any comments on it.

While pulling a slalom skier at 3000 rpm the engine temp spikes up to around 200 degrees and the engine control shuts the throttle off. At the same time, I can drive without a skier at the same rpm without issues. Also I was pulling wakeboarders/trick at 2000 rpm range for hours without an issue. At first I thought that weeds had clogged up the intake or the impeller at intake was shot but all looked good. I have read about thermostat chang outs, or pieces of junk in the tstat, and oil cooler lines plugged. Thus I am prepared to check those things but any other thoughts given the lower rpm's and no issues?
Thanks!

Remove the large hoses at both ends of your trans cooler. I would bet it is plugged up. Backflush it with a garden hose.

jakethebt
08-27-2013, 05:38 PM
I see that you only have a few posts. You may or may not be familiar with the early LT-1 cooling issues. Some of the above posts are talking about this cooling issue. The original LT-1 engines had a few cooling issues. If you are unaware of those, that would be the first thing I would check. I will see if I can find the thread and post the link here later. Basically there is a cross over tube that connected cooling water at the back of the heads. Being in a boat and the engine being mounted with the front much higher than the back caused air to be trapped at the front of the heads causing overheating. There is a simple and cheap kit to fix this that plugs the rear holes and adds a cross over tube at the front of the heads. This would be my primary suspect for overheating since you seem to suffer the issue when pulling a skier. This would put you nose high and under load, making this particular issue worse.

Take a picture of your heads both front and rear and we can tell you right away if your Lt-1 has the fix. If not, there was a part number and a dealer on here that's sold them for around $25.

johnboat
08-27-2013, 10:32 PM
I will take a look and snap some pics this weekend if needed. Thanks all for the help, if you find the link that would be great but I will do some seaching also.

jakethebt
08-28-2013, 07:39 AM
This is the one that I was thinking of...

http://www.mastercraft.com/teamtalk/showthread.php?t=31626&highlight=lt-1

The thread is a bit different but the info sound like it has identified the cooling problem and a fix. There are a 100 other threads on LT-1 overheating... so if this does not work maybe one of the other ones will.

Kevin@MWMC
08-28-2013, 08:32 AM
Just an FYI for everyone, the kit that MasterCraft was using for the Service Bulletin is no longer available. I've had 4-5 people call this year for this kit and it is no longer made. You could try to call some dealers and maybe get lucky and find a dealer that might have an extra kit laying around. We sold our last one roughly 2 years ago.....



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Kevin@MWMC
08-29-2013, 06:36 PM
Please see here: http://www.mastercraft.com/teamtalk/showthread.php?t=31626&page=11

johnboat
09-04-2013, 10:44 PM
Thanks for the info, the change had my boat running at 160 F all weekend!

jakethebt
09-04-2013, 10:54 PM
What did you end up changing?