Overheating

[JohnnyBlueToes]

Gauge is reading around 165 or 170 once up to temp and pulling away from the dock. Everything appears fine until you run the boat hard for a bit and then the temp starts to climb - typically between 170 and 200. Slowing the temp will climb up to 240. You can shut it down and fire back up 30 seconds later and the gauge reads 160 again. This leads me to believe I've maybe got a gauge problem. Maybe a sending unit? Checked the impeller - like new. Engine does not act like or smell like it is running hot.

Maybe of note - I blew up my heater core over the winter so I capped the lines. Then I started having the problems above and I thought this was maybe creating a problem, so I made up a hose to tie them together (was thinking this was why my base temp was 170 vs. the usual 160).

Any light that could be shed would be appreciated. Thanks - JBT

[edwin]

You blew up the heater core in my boat?!?

My guess is I'd check out the sending unit. The boat had that problem once, believe it was in 2004. I swapped the impeller, t-stat, checked the circ pump for good flow, etc. It read high but never did it actually get hot. After all my trouble shooting it never did it again.

[Big Mac]

Gauge is reading around 165 or 170 once up to temp and pulling away from the dock. Everything appears fine until you run the boat hard for a bit and then the temp starts to climb - typically between 170 and 200. Slowing the temp will climb up to 240. You can shut it down and fire back up 30 seconds later and the gauge reads 160 again. This leads me to believe I've maybe got a gauge problem. Maybe a sending unit? Checked the impeller - like new. Engine does not act like or smell like it is running hot.

Maybe of note - I blew up my heater core over the winter so I capped the lines. Then I started having the problems above and I thought this was maybe creating a problem, so I made up a hose to tie them together (was thinking this was why my base temp was 170 vs. the usual 160).

Any light that could be shed would be appreciated. Thanks - JBT

Bad thermostat or blocked transmission cooler need to be ruled out before assuming a gauge problem, IMHO. Either of those things are more common than a bad gauge or sender, I think.

[RTS]

Gauge is reading around 165 or 170 once up to temp and pulling away from the dock. Everything appears fine until you run the boat hard for a bit and then the temp starts to climb - typically between 170 and 200. Slowing the temp will climb up to 240. You can shut it down and fire back up 30 seconds later and the gauge reads 160 again. This leads me to believe I've maybe got a gauge problem. Maybe a sending unit? Checked the impeller - like new. Engine does not act like or smell like it is running hot.

I've got to guess that if you were running at 240 degrees, you'd know it by the smoke/smell/sounds coming from your engine compartment.

Also, with the engine shut down (no cooling water coming in) it's unlikely that your Monsoon would cool from 240 to 160 in 30 seconds.

Sounds like a sending unit to me...or somethig else electrical.

Edited July 3, 2007 by rts

[UWSkier]

Our '01 has done the same thing in the past. The '01 is notorious for having a bad gauge ground. Run another heavy gauge ground wire from the bus bar to the negative battery terminal. That and you can check the grounding of the sending unit itself as that can cause issues.

I agree with the above post. If resetting the gauges by power cycling them returns your reading to a perfect 160, it's a gauge issue.

[Gordo]

First thing I would do would be to check for junk in your transmission cooler - lake debris, pieces of an old impeller?.

[JohnnyBlueToes]

You blew up the heater core in my boat?!?

Don't recall blowing out the heater core covered in the orientation. Pulled and drained them, but failed to blow out. Live and learn, School of Hard Knocks seems to leave lasting impressions (similar to the credit card machine when they imprint my card to pay the bill!), lesson learned.

Tranny cooler screen has been checked - clear. Will take a look at the sending unit - want to say this a fairly inexpensive part that can be swapped easily. Can somebody confirm to me that this is located on the top of the intake manifold toward the front of the motor?

Ground should be easily temped in as well. Appears to solve the problem I can get a little fancier w/ the install.

Thanks to all for the responses.

[edwin]

Believe there's two sending units, one up top in the front of the engine by the t-stat with two wires coming out of it. Second one is located somewhere else

[JohnnyBlueToes]

Talked w/ the Service Manager at the local dealer when checking to see if they had a sending unit in stock. He said it is rare for them to go out and suggested pulling it out and cleaning it up with a wire brush. Pulled it tonight and found some mild deposits on it which I was able to clean up. Also went ahead and ran a ground wire from the bus to the battery - leaving disconnected right now to see if the sending unit was the issue. Will drop the boat in the water in the morning and see if I've resolved anything.

Edwin - Don't know about a second sending unit, but the one up front has a single hot wire coming out of it. The unit self grounds on the manifold (this according to the Malibu Service Manager)

JBT

[edwin]

Edwin - Don't know about a second sending unit, but the one up front has a single hot wire coming out of it. The unit self grounds on the manifold (this according to the Malibu Service Manager)

JBT

Hope cleaning up the deposits takes care of the issue. Please tell me you haven't been using my boat in salt water.

[Woodski]

A weak impeller can yeild the same results. Just not pumping enough water through the system under high loads. Replace if the grounds or electrical fix's don't cure the problem.

[ffdawg]

I would agree with the above poster that said if you actually are running that hot, you'd notice. I recently had some debris in my tranny cooler and my temps were pushing above 170. It made a noticeable "hot" smell in the boat like a hot hose or belt, or something beginning to melt/burn. You'd recoginze it as not normal.

Keep us informed with what you find, please.

[JohnnyBlueToes]

It was a good morning......

Started w/ a 5:15 set behind a new acquaintances RLXi (He lives on the lake and now were set to ski once a week for the rest of the season). Got two pulls in before boats were coming from all directions. Jammed back to the barn and picked up my boat a nd ran it back down to the launch. Dropped it in and appeared that hings had gotten better, but temp was still running up to around the 200 mark and depending on speed would fluctuate between there and 170 or so. Shut her down and hooked up the new wire run from the grounding bus to the negative post of the battery. Again, things seemed to get better, but now things were running between 160 and 180. With the motor running I pulled the connector on the sending unit to see if I could get things to re-set. Plugged it back in and things stabilized at 160 and looked good. Called a buddy who grabbed his wife to run down to the lake (lake was getting really busy now and I looked pretty pathetic out there by myself on 4th of July) and we had a cup of coffee and watched the Wally Fest while cruising around for an hour or so. Temp held steady at 160 the entire time. By the time my friends got to the launch they had closed the gate as the parking lot was full - the ranger was letting boats in 1 for 1 coming out. This was 9:15 in the morning.

Side-note; after adding the additional ground my oil pressure gauge seemed to stabilize. Prior it had been fluctuating between 40 and 70 when at idle and then pegging at 80 plus when under way. Now it is reading a steady 70 or so.

Thanks to everyone for there input. Special plug for Paul over at Bake's Marine (Service Manager at my Local Bu Dealer), he gave me a couple things to try on my own before suggesting bringing it into them. He called me right back after leaving a message with guy at the front desk. This the day before the 4th when they were slammed. Couple things he gave me were 1) if you can hold your hand on top of the exhaust manifolds it isn't overheating 2) try cleaning the sender with a wire brush before replacing 3) As he didn't have a sending unit in stock, said just go to Napa and they could likely match mine up to get me going.

It's good to be back on the water........

[ultrachill]

It was a good morning......

Started w/ a 5:15 set behind a new acquaintances RLXi (He lives on the lake and now were set to ski once a week for the rest of the season). Got two pulls in before boats were coming from all directions. Jammed back to the barn and picked up my boat a nd ran it back down to the launch. Dropped it in and appeared that hings had gotten better, but temp was still running up to around the 200 mark and depending on speed would fluctuate between there and 170 or so. Shut her down and hooked up the new wire run from the grounding bus to the negative post of the battery. Again, things seemed to get better, but now things were running between 160 and 180. With the motor running I pulled the connector on the sending unit to see if I could get things to re-set. Plugged it back in and things stabilized at 160 and looked good. Called a buddy who grabbed his wife to run down to the lake (lake was getting really busy now and I looked pretty pathetic out there by myself on 4th of July) and we had a cup of coffee and watched the Wally Fest while cruising around for an hour or so. Temp held steady at 160 the entire time. By the time my friends got to the launch they had closed the gate as the parking lot was full - the ranger was letting boats in 1 for 1 coming out. This was 9:15 in the morning.

Side-note; after adding the additional ground my oil pressure gauge seemed to stabilize. Prior it had been fluctuating between 40 and 70 when at idle and then pegging at 80 plus when under way. Now it is reading a steady 70 or so.

Thanks to everyone for there input. Special plug for Paul over at Bake's Marine (Service Manager at my Local Bu Dealer), he gave me a couple things to try on my own before suggesting bringing it into them. He called me right back after leaving a message with guy at the front desk. This the day before the 4th when they were slammed. Couple things he gave me were 1) if you can hold your hand on top of the exhaust manifolds it isn't overheating 2) try cleaning the sender with a wire brush before replacing 3) As he didn't have a sending unit in stock, said just go to Napa and they could likely match mine up to get me going.

It's good to be back on the water........

Hey y'all...

I've been through the gamut on my own wakesetter. I've also talked with Paul at Bake's (that guy ROCKS btw).

If anyone has any additional help, I could sure use it. I've been over so many buliten boards and posts, and I think I'm almost out of ideas. I've also been over this problem with Paul @ Bake's. I'm missing something simple, I know, but it's been over 3 weeks now.

Issue:

All this started happening since someone shut the water off when I was winterizing last fall, and I burned out the impeller. I've had years of experience working on cars, heavy machinery, motorcycles, etc, so I'm not a newbie to technial issues (electrial, mechanical, cooling, etc).

Symptoms: Overheating (200+ and shuts off @ 205) under load (20mph+), otherwise it runs at normal temp (160-170). runs fine at idle. pull a skier, and it heats up in a few minutes to 205, then the ECU stops sending spark. I shut it off, and restart. The temp comes back down to normal (160).

Right before the temp skyrockets, the heater will blow cool air just as the temp reaches about 190ish. As soon as I start it up again, the heater will blow hot air again. (this entire scenario is typical of everything I've read and goen through already.

From the bottom:

I've checked the brass water inlet for blockage (none), the valve is open on the inlet hose, I put a new impeller in a couple months ago (yes it's still in great shape and water runs freely at idle when disconnected from the tranny cooler - no fins gone, and all fins are complete and very pliable), changed the t-stat, swapped waterpumps with a known-good one, cleared the tranny cooler of some small debris.

None of this has helped, and I'm going on week 3!

The only thing I can think of is that my new t-stat is bad (Stant brand has never failed me but I'm going to just remove it tonight), or there's blockage INSIDE the inlet hose.

Does anyone have ANY other suggestions? Please?

-shaun

[VinRLX]

If you want to check the inlet hose, unhook it from the impeller and poor water down it. You should hear water hitting the driveway.

What year is your boat (profile info)?

Did you try 1, 2, and 3 from the above post?

Is it possible to install the 'stat upside down or otherwise incorrectly?

[wienrdog]

Have you taken a good look at the impeller. It's pretty unusual, but it could be slipping on the hub. I've heard of it before. It does sound like the water intake is insufficient when running at speed. You could be spinning the impeller fine after a stop and when at idle, but when you move past idle, the hub starts to slip & you don't get the throughput you need to cool the engine - it actually sounds like the water flow goes down from when at idle.

You could also have a leak in the inlet hose between the lake & impeller that doesn't open until you spin the impeller up to a certain speed (get enough vacuum) & when it opens, you start sucking mostly air instead of water.

I don't really think it's the t-stat because it will open to let hot water out of the engine (and let cool water in to replace it) - you can always test it in a pan of water with a kitchen thermometer as backup. Saw a diagram of the water flow not too long ago, but can't find it now. It could be that it's stuck part way open, which would be fine at idle, but not open enough at speed. That wouldn't explain the heater though. The heater will draw water from the side of the engine, bypassing the t-stat. The heater makes me think that you've stopped moving water through the engine all together.

Edited July 13, 2007 by weinrdog

[Baddog]

Talked w/ the Service Manager at the local dealer when checking to see if they had a sending unit in stock. He said it is rare for them to go out and suggested pulling it out and cleaning it up with a wire brush. Pulled it tonight and found some mild deposits on it which I was able to clean up. Also went ahead and ran a ground wire from the bus to the battery - leaving disconnected right now to see if the sending unit was the issue. Will drop the boat in the water in the morning and see if I've resolved anything.

Edwin - Don't know about a second sending unit, but the one up front has a single hot wire coming out of it. The unit self grounds on the manifold (this according to the Malibu Service Manager)

JBT

The one in front with the single wire sends the temp to the computer, not the guage.

Edited July 13, 2007 by Baddog

[ultrachill]

OK, I think I got it! Weinrdog, thanks for the reply as I would have used your thoughts to go further on this thing. I had checked the splines on the impeller, and all the hoses are in great shape

I took out th thermostat last night and the temp finally got up to 160 after running it pretty hard. Since she's running cool now, I'm pretty sure it the t-stat. It was brand new too! I'll stick a new one in so I can get to to proper operating temp and have a heater for those cold mornings.

I'm back in business! I was running out of options.

Thanks to all who spent a few minutes thinking about this on my behalf.

Cheers!

Have you taken a good look at the impeller. It's pretty unusual, but it could be slipping on the hub. I've heard of it before. It does sound like the water intake is insufficient when running at speed. You could be spinning the impeller fine after a stop and when at idle, but when you move past idle, the hub starts to slip & you don't get the throughput you need to cool the engine - it actually sounds like the water flow goes down from when at idle.

You could also have a leak in the inlet hose between the lake & impeller that doesn't open until you spin the impeller up to a certain speed (get enough vacuum) & when it opens, you start sucking mostly air instead of water.

I don't really think it's the t-stat because it will open to let hot water out of the engine (and let cool water in to replace it) - you can always test it in a pan of water with a kitchen thermometer as backup. Saw a diagram of the water flow not too long ago, but can't find it now. It could be that it's stuck part way open, which would be fine at idle, but not open enough at speed. That wouldn't explain the heater though. The heater will draw water from the side of the engine, bypassing the t-stat. The heater makes me think that you've stopped moving water through the engine all together.

[ultrachill]

VinRLX,

If you didn't catch my last post, I think I got it figured out. The new thermostat was bad - it runs cool after I took it out.

Btw, the boat's on the water and it's a wakesetter xti21 (DD). I was able to blow on the impeller's inlet hose and was able to push the water out quickly enough to hear bubbles right away with very little back pressure too.

I also took all the hoses off from the impeller and up. after starting the engine for just a few seconds to make sure the water flow was at least fine at idle, I connected each piece in order up to the water (circulation) pump inlet, and started the engine after each piece was re-connected. A little water got inside, but it's a boat right?

Well hopefully this post will serve someone well... and is confimation that sometimes new thermostats don't actually work!

cheers-

shaun

If you want to check the inlet hose, unhook it from the impeller and poor water down it. You should hear water hitting the driveway.

What year is your boat (profile info)?

Did you try 1, 2, and 3 from the above post?

Is it possible to install the 'stat upside down or otherwise incorrectly?

[ultrachill]

Hi. Thanks for everyone's help so far. all good thoughts! I wanted to give an update.

I put another new t-stat in and it did the same thing.

It runs 100% below 160 degress w/o a t-stat and overheats at around 20 mph with one in. I didn't notice until this weekend that the design of my old one was a little different.

I went to the parts store and saw they had one just like my old one, and they called it a high-flow t-stat. The one I got was from Mr. Gasket and looks like this one: http://store.summitracing.com/partdetail.asp?part=MRG%2D4363

The ones I put in last week looked like this:

http://www.speedyperformanceparts.com/imag...h/powerstat.jpg

I got the 160 degree t-stat and tested it in the kitchen with a baking thermometer, and it opened up right at 160. So I put it in pointed side up in between the housing and the riser (not touching the intake manifold).

With the other thermostats (low-flow deisgn) it overheated aroudn 20 mph.

With the high flow t-stat, it took at little while longer to overheat (heater also went cold right when the temp gauge hit 190-ish, so it's not a faulty sensor), but it still did, but at over 30 mph only. I actually had to get it up to 40 to get it to overheat, but I loaded up the ballast and put the wedge down with PP set at 25 mph, and it didn't overheat at all!

So I'm better, but not quite out of the woods yet... It used to go 45 solid and not overheat at all.

Has anyone ever drilled a small hole in the edge of the t-stat to allow more water flow?

I'm on the right track I know but still missing something.

Cheers-

Shaun