View Full Version : 2001 X30 330hp LTR overheating

06-02-2014, 10:45 PM
Hi, I just took my 01 330hp LTR Mastercraft out on the lake for the first time, and the temp went uptoo 220, pushing 240. I shut it down and cooled it off, then drove got it back to the dock. it ran perfect all last summer no issues, i winterized it and now its running very hot, i just replaced the impeller, the old one looked fine though, i changed the thermostat, the old one was rusty, i thought maybe it stuck closed over the winter but when I hung it in hot water it moved, I put a new one in anyway, the old one was installed on top of the spacer block, does any one know if thats where it goes or does it install right at the block? i installed it the way it came out, on top of the spacer point facing up? I have a junction to connect a hose inline and ran it up again and it is still running hot so the gauge says 210 to 220. but lots of water coming out of the exhaust ports out back. I used a digital thermometer around the whole block its pretty steady around the top and thermostat housing at 143, down port side by the spark plugs it ranges 145 to 160 on the starboard side the thermometer is off the chart at 220 plus, could thyis be manifold? can anyone give me some insight please. the top of the exhausht elbows are at 97 to 100, not sure what to do know,:cool:

06-03-2014, 10:31 AM
silly question, but did you watch the motor run? i've summarized and cranked in the driveway only to see water pouring out of a hose i forgot to reattach. also, when my raw water pump was failing, it leaked a fair amount of water out of the shaft area. i've also not tightened the housing on my thermostat enough and had water leaking out of the seal. it sounds like you have the t-stat installed correctly. it's a clamshell design and the t-stat sits in-between them. iirc, the pointy end is down. i guess a long shot may be if you have a heater and it is spewing water from a leaky core.

another area to look for water restriction is the bottom of the transmission cooler. i also just had my water circulation pump start to go bad. does it make any funny noises? that was the clue for me as the bushings were shot and the pump was making a clanking noise. i ran the boat with the belt off for a bit in the water to narrow down the noise. the pulley was also a little wiggly and not real smooth to turn.

i'm not sure how any of the above would make the port side cooler than the starboard. if you take out the drain plug on the starboard block does it spew water like when you winterized?

hopefully it will be a quick fix. good luck.

06-03-2014, 12:14 PM
I did watch the motor run, I took it up to 2000 rpm and couldn't see any leaks, I have the thermostat with the point end up? I guess the next step is to check the transmission cooler, when i winterized I did not pull the drains, I just ran marine antifreeze through the system from the hose pickup until it came out the exhaust ports. I will pull the block drains and flush water through, I didn't notice the circ pump making noise but will watch it again, I do have a heater but don't know where the core is? I think the fan is behind a panel under the helm, so I'll check that out as well. I will try these and post my results, thanks for the help

06-03-2014, 12:24 PM
your heater core is attached to the fan. mine is under the helm behind the panel the sub is installed in. usually the water runs out at the drivers feet if its bad. likely not your issue unless you have a puddle of water under the helm.

06-03-2014, 12:42 PM
that will be where my heater core is, but no water around that area.

06-03-2014, 02:49 PM
Don't know specifically about the LTR, but most if not all thermostats install with the point and spring down. Maybe someone else with specific knowledge about your engine will chime in.

06-03-2014, 03:42 PM
Make sure raw water impeller is installed correctly. A few have used the narrower (1 7/8" vs 2") version by accident as they look and fit almost identically. A few have had the key fall out of the shaft during assembly, and a few have had the splined versions center delaminates from the rubber which all resulted in little or no cooling water flow.

06-03-2014, 07:15 PM
Im just about to head out to the boat, I will take another look at the impeller, mine is the splined version. as well I install the thermostat on top of the spacer block point up. I will try to flip this as well. Thanks

06-03-2014, 09:16 PM
okay took the new impeller out and compared it to the old one seems to be an exact match. dipped it in soapy water and reinstalled it, pulled the hose from the circ pump and ran water through pulled the plug on the starboard side and flushed water through for 10 min, water flowed good and steady out the hole. flipped the thermostat from point end up, to point end down, this thermostat has no spring. started up and ran for 10min right at 160 then inched its way back up to 220, put my hand on the raw water pump and inlet hose, both are cold as the water going in, speed up the motor but this did not cool it down, again lots of water coming out the exhaust, and the water is cold, i thought it would be hot? not sure what to do Know? circ pump is not squealing or leaking from the hole, as Im using the hose connector i have no shut off valve for the through hull water runs out of it but doesnt look like im sucking air, plus this happened in the lake originally,

06-03-2014, 09:25 PM
There are two water pumps, the raw water impeller feeds water to the engine and the regular water pump circulates it through the engine. This second pump is belt driven (not off the crank) where you'd find the normal water pump on a truck. 95.9453% sure that's what you need to replace. Then double check you've got the thermostat in right side up.

06-03-2014, 11:19 PM
I think you may be right, just doesn't seem to have any pressure to push the hot through the thermostat. I took the stat out and ran it up, and what hot water was left in the block came out the exhaust. then ran cold the rest of the time. then i reinstalled the thermostat right at the block and it overheated again pointy side up which I believe is the right way. I will have to buy a circ pump and hope for the best i guess.

Table Rocker
06-04-2014, 10:18 AM
The circulation pump is not going to be your problem. They are very simple with metal impellers. When they go bad (seals & bearings), they still pump but also leak through the weep hole in the bottom.

On thermostat installation, the pellet (part that looks like the back of a bullet) goes in the hot water. How many thermostats are in your boat? It sounds like you have two since you mentioned one right at the block.

06-04-2014, 10:27 AM
Could be that the vane on the water pump is corroded enough that the fins are gone or impeller came off the shaft. Cold water coming out is either a bad water pump or (my guess) a bad thermostat. Pull thermostat and run it. If water comes back warm from exhaust, the new thermostat is likely no good. This does happen sometimes.

Table Rocker
06-04-2014, 10:35 AM
I guess it could have air in the block as well. If the LTR is supposed to have two thermostats (I have no idea) I think I would drill a couple of 1/16" holes in the thermostat on the block to help purge the air that open cooled boats are always going to get.

Engine Nut
06-04-2014, 10:51 AM
Some of those engines were built with two temperature measuring components. One was a single wire sensor that was used to drive the gauge and the other was a two wire sensor that sent a signal to the ECM. Check and see if you have two separate temp senders, they are threaded in the intake manifold on either side of the thermostat housing. Find someone with a scan tool that will read the temperature signal at the ECM. It is conceivable to have the sender for the gauge reading one value ant the one for the ECM another ... trust the two wire sensor. By the way, the thermostat goes into the top part of the housing with the sensing pellet down.

06-04-2014, 12:18 PM
ok thats the way i installed the new thermostat, in the top part of the housing with the sensing pellet down which make the point part up. I did run it without the thermostat and the rest of the hot water came out of the block through to the exhaust, and engine ran cold from there. I put the new thermostat in some hot water and it opened up fine. I do have a sender on either side one is light brown right at the thermostat area and the other is on top of manifold but the gauge seems to be working cause it stayed cold when I ran it with the thermostat out. theres only one thermostat, and I moved it down to the block to see if it would work there but still over heated, I dont know, I have a Quicksilver thermostat with the spring for 350 mercruisers maybe i will try this be fore I pull the circ pump. thanks for the help

06-04-2014, 01:00 PM
There are 2 temp sensors. One runs the guage and mefi to determine proper fuel based on engine temp. The other also goes to mefi and is a hi temp switch. When it grounds out, the mefi sends a check engi e light.

Based on the fact that boat is running cool without thermostat in, I think you have a problem with the new one. Very rare for the engine water pump to fail. I'd spring for a new 160 thermostat from auto parts store, install, and try again. Your engine should only have 1 thermostat unless it is an

06-04-2014, 05:26 PM
Hmm. I have a 2002 Sammy D LTR and believe I only have one, 2 wire temp sensor on top part of the thermostat which I believe controls all. There's a plug (painted, original) on the side where the older style single wire sensors went.

06-04-2014, 06:19 PM
well looks like it was the thermostat, i put the mercruiser style thermostat in and ran it up
and its holding steady temp although its a 140 the temp is holding steady just above that 150, I ordered a 160 thermostat for tommorrow and will try this out, but so far so good.. Just suprised that the new indmar thermostat was not working, just glad I had the 140 around to try it, and thanks to Rossterman for mentioning to try another thermostat. I'll post one more time when i install the 160 tomorrow, Thanks all

06-04-2014, 06:24 PM
Hmm. I have a 2002 Sammy D LTR and believe I only have one, 2 wire temp sensor on top part of the thermostat which I believe controls all. There's a plug (painted, original) on the side where the older style single wire sensors went.

Could be. Mine is the tbi predator so could be different but thought the mefi's were pretty similar. On the tbi model, there is a single wire temp switch up on front edge of the manifold by the thermostat and the two wire temp sending unit a few inches away at sitting vertically in the manifold.

06-04-2014, 07:43 PM
Well, if it's just that thermostat it's way better than a water pump! Glad to hear it sounds like TommyV is going to be back in the water.

06-05-2014, 08:05 AM
Great job guys, This is great team work!!

06-06-2014, 10:25 PM
Ok everybody I installed the 160 thermostat not the indmar style but the mercruiser syle with the spring, Sierra part# 18-3649. Works like a charm holding 160 on the nose. So in the end it was great team work, with the new raw water impeller now in. I did oil and filter, just cause it did reach 220 out on the Lake it probably broke down the oil as well, I used Mercruiser semi synthetic 25w-40 filled the tank added a little stablilizer, and some injector cleaner, she's purring like a kitten. Thanks again all, I'm now off to the Lake for the weekend.

06-07-2014, 09:13 AM
sure glad so hear it worked out for you.