leaking heater pump causing overheating?

This past weekend we spent the morning boating with no issues. Later when the engine was in neutral and we were filling the ballast I got a ECT Higher Than Expected and my engine temp was over 200. I checked the coolant level and it was fine. I shut it off and did some reading here online. I read where if I got up to speed/rpms up the temp would come down and sure enough it dropped to 165 in a matter of 20 seconds as long as I had the rpms up. When i stopped and was just in neutral the temp would start climbing. I called it a day, come home and put the boat away. I read that the heater pump was a common problem and would leak out coolant. I checked the coolant tank and it was completely empty. I pulled the heater pump off and there is definitely dried purple on the bottom of the pump. So I'm guessing that the leaking heater pump was the cause of the high engine temp? We did have the heater running for several hrs so that all makes sense that the coolant was slowly leaking out but why would the coolant tank be full if that was happening? And then why would the tank be empty after sitting for a few days?

Can I replace the pump with any pump or is this made for coolant and not water? I'm assuming any pump will do.

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Originally Posted by 996scott

This past weekend we spent the morning boating with no issues. Later when the engine was in neutral and we were filling the ballast I got a ECT Higher Than Expected and my engine temp was over 200. I checked the coolant level and it was fine. I shut it off and did some reading here online. I read where if I got up to speed/rpms up the temp would come down and sure enough it dropped to 165 in a matter of 20 seconds as long as I had the rpms up. When i stopped and was just in neutral the temp would start climbing. I called it a day, come home and put the boat away. I read that the heater pump was a common problem and would leak out coolant. I checked the coolant tank and it was completely empty. I pulled the heater pump off and there is definitely dried purple on the bottom of the pump. So I'm guessing that the leaking heater pump was the cause of the high engine temp? We did have the heater running for several hrs so that all makes sense that the coolant was slowly leaking out but why would the coolant tank be full if that was happening? And then why would the tank be empty after sitting for a few days?

Can I replace the pump with any pump or is this made for coolant and not water? I'm assuming any pump will do.

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Mine did the same thing...my older Max...I had to take it to Marine Products downtown and they replaced the pump and it worked no problem. The problem is, I don't trust the heater anymore and don't use it much...if at all. I have a new Max and still watch the temp guage if the kids run it.

Fuilds....not really sure, but my guess would be that its circulating all the fluid in the system and not just going into the pump and it quite a bit. Once it all settles and cools down, the amount that was burned off really shows itself and is enough to show the tank empty. Just a thought, I could totally be wrong. The guys at Marine Products did it fast and I felt it was worth the money in case it happened again...it would be on them.

This happened to me too.

I did two things

1 - unhooked pump terminals from starter, unhooked hoses from pump and bypassed it by connecting hoses together.

2 - sourced the lower part of the pump on Amazon and replaced it with a new seal.

This fixed my issue for ~$35 and then topped off with coolant.

Also - you’ll have an airpocket in the coolant system so I suggest once you top it off that you bring extra to the lake because your reservoir will likely be empty again as the airpocket works itself out unless you properly replace all coolant as per indmar.


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SHURFLO 94-800-00 Model 4008... https://www.amazon.com/dp/B00SQ4F4V2...p_mob_ap_share


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Just curious. Is it a gasket leaking or is the pump housing cracked?

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OP, you probably know, but if you are having this problem it won’t matter whether or not you use the heater. This pump is always running circulating coolant to the heater unit. You could bypass and disconnect as mentioned above. I did that for one season when I had the problem until replace with new pump at end of season.

I had the issue. My Supra had a crack. That was two summers ago. Slow leak.

It's a cheap little pump, I am sure an upgrade is out there.

It's just an RV circulation pump.


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Originally Posted by larry_arizona

It's a cheap little pump, I am sure an upgrade is out there.

It's just an RV circulation pump.


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Problem is Heatercraft charges $60 for shipping alone.

My pump works like a charm now. No leaks.


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Originally Posted by eder10986

SHURFLO 94-800-00 Model 4008... https://www.amazon.com/dp/B00SQ4F4V2...p_mob_ap_share


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Thanks for the link, I knew I had seen a link for this the other day but couldn't find it. I will order and see if this takes care of it. thanks

thanks guys for all the help. I ordered the new part and will put it all back together, refill the coolant and keep an eye on things. The coolant is propylene glycol and needs to be 50/50 mix with water right? Where is the best place to buy it?

I got it at Oreillys. Only place near me that actually carried it without purchasing thru dealer

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Originally Posted by Mxmark4

I got it at Oreillys. Only place near me that actually carried it without purchasing thru dealer

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Napa has premix propylene glycol, Brand name Sierra Peak. Used it on my Mojo and SA

Also Prestone Low Tox is readily available https://uploads.tapatalk-cdn.com/202...98e7f5d975.jpg


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Where is the pump located? Is it easy to see for regular inspections?

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Originally Posted by cucv

Where is the pump located? Is it easy to see for regular inspections?

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Usually towards the upper forward area of the engine bay behind a access panel. Very easy area to service


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Interesting that the pump is designed for Rv fresh water pumping. The water temperature going through would be at ambient whereas this application would be at the coolant temperature. Could that be an issue with the case cracking?

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Originally Posted by larry_arizona

Also Prestone Low Tox is readily available https://uploads.tapatalk-cdn.com/202...98e7f5d975.jpg


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This is also what I used to refill coolant.


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Quote:

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Originally Posted by larry_arizona

Also Prestone Low Tox is readily available https://uploads.tapatalk-cdn.com/202...98e7f5d975.jpg


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Can this be added into the OEM Indmar coolant ( mixed with) or do i need to drain/flush the whole system and refill with this?

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Originally Posted by 996scott

Can this be added into the OEM Indmar coolant ( mixed with) or do i need to drain/flush the whole system and refill with this?

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All propylene glycol coolant brands are compatible.

Peak or Prestone likely make and rebrand for Indmar.


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Quote:

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Originally Posted by cucv

Where is the pump located? Is it easy to see for regular inspections?

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Mine is located at the rear port side of the engine compartment towards the bottom. Not terrible to get to but not great either.

awesome, thanks. With 300+ hrs on the clock I guess I should probably just drain and flush the whole thing since Indmar recommends it at 300hrs.

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Originally Posted by 996scott

awesome, thanks. With 300+ hrs on the clock I guess I should probably just drain and flush the whole thing since Indmar recommends it at 300hrs.

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Technically it's every 2 years or 300 hours whichever comes first.


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Just a follow up on this in case it helps anyone out. I got a new heater pump and replaced the cracked one, drained the coolant out and replace with new coolant(since i was at 300+ hrs). I followed the instructions from Indmar. Spent a few hrs on the lake last week and the engine temp stayed nice an constant around 160. After leaving it overnight I checked the level in the coolant tank and it was a bit low so i topped it off. Everything seems to be great now.

Once I had mine fixed, had to top-off the levels 1-2x and all was consistent after that.


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