Replacing coolant/ ECT code

[korey]

Reviving this... I had the same symptoms. Bypassed the heater for the end of summer and coolant loss went away so I could be fairly certain that it WAS somewhere in the heater. Get to dreaded winterization day yesterday and decide to clip the wires on the pump, pull it out, and have a closer look. There were obvious signs of dried coolant on the bottom of the heater pump. 100% the culprit, same as eder above. I decided to tear into the pump and see what I could see. They’re on backorder from what I can tell.

[[disclaimer]] Although I am a P.E. level Mechanical Engineer, with a couple of decades experience in industrial automation (including vast experience with pumps); I didn’t design this pump, and I had a beer in hand for this activity. I’m guessing at a few things and making a few more up. Following my advice could result in a voided warranty…

First some info. I hope some of this comes in handy for someone down the road. The pump is Heatercraft part number 4838-111-A65. That is a rebranded/private label Shurflo pump – Shurflo makes it exclusively for Heatercraft. The “A” in the part number says it’s for OEM applications. I believe the 4838 in the part number describes it’s temperature and fluid type specification, but not 100%. This pump has both thermal and pressure relief valves built in – as you’d want when running 200 degree engine coolant! I didn’t call my dealer, but heatercraft has a similar model (the part number does not match perfectly) for $150 – it is backordered. Bakes has another similar model, but it seems like its for a shower, NOT engine coolant.

Like I said, I took the pump apart and nearly instantly found 2 problems.

1)There was a sheared origin in the temperature relief valve (the widget on the bottom with the wires running to it.
2)The adjuster on the pressure relief valve (the other widget on the bottom with a little hex key adjuster) was adjusted all the way in, with he set screw now falling inside the housing.

I’m not too sure which one caused the leaking for me, but I fixed both for free (I had an oring kit to match the damaged ring). I wont REALLY know if it’s fixed until spring when I really get to run it, but I reassembled everything, got it up to temp on the hose and there was no fluid coming from the bottom of the pump!

I should have taken pictures, but I didn’t… beer. The pump is a diaphragm style pump with 4 pistons/diaphragms. The 12v motor turns an eccentric cam (I prefer to call it a wobbler) that moves water from the inlet to the outlet. The attached image is of a similar pump. Like I said above, my problem was likely in the relief valves, but I could also see problems occurring because the diaphragms are ruiptured (replace the main body, part 2 in the diagram), or a bad gasket between parts 2 and 4 (the gasket shows is NOT the same as the gasket on the pump on my boat).

Again, I hope my experience helps someone in the future.

[eder10986]

This is awesome I’ll have to check on mine.

My issue is also that I don’t actually think it’s running. At all. I do have to figure that out as well - I have two loose terminals hanging out that I haven’t figured out he’s they’re for although I don’t think they’re for the pump because I believe it used a harness?

I think I’m going to also take mine apart and see if I can figure o if wtf is up with mine.


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[parrothd]

This is awesome I’ll have to check on mine.

My issue is also that I don’t actually think it’s running. At all. I do have to figure that out as well - I have two loose terminals hanging out that I haven’t figured out he’s they’re for although I don’t think they’re for the pump because I believe it used a harness?

I think I’m going to also take mine apart and see if I can figure o if wtf is up with mine.


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The housing usually cracks and you can easily replace it.

SHURFLO 94-800-00 Model 4008 Complete Upper Housing https://www.amazon.com/dp/B00SQ4F4V2...ing=UTF8&psc=1

[BigOrange]

So I’ve got my new heater loop pump installed and and ready to replace all coolant since I had mix of multiple fills and even water in mine due to the failures last summer. Two questions:

1) I read that pulling the ~2” Hose off block on lower starboard side is best way to drain. I’ve done that. Is there any further steps to take to get any remaining coolant out.

2) is there any tricks for filling to avoid air bubbles? I was thinking of raising the surge tank top (return) line off, holding it higher than all the engine and using a funnel to fill while the surge tank cap is off.

Thanks!

[BigOrange]

Bump to get back above the spam threads. Any thoughts? Thanks!

[parrothd]

Bump to get back above the spam threads. Any thoughts? Thanks!

Just add coolant to the resivior until it's full, then add more when needed.

[HFarr]

Yep, honestly that simple.

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[korey]

Yep, as others have said, there's nothing to it. I went a touch overboard and pulled the thermostat housing when draining to be more sure it drained completely. hat wasn't worth it, I wouldn't do that again.

I miss my boat. Snow showers forecasted Saturday morning here in KY...

[BigOrange]

Thanks everyone. Will get it filled and ready to run on the hose soon. Just have to wire up the new coolant pump.

The wx needs to warm up in a hurry. We are usually in the water in about 2 or 3 weeks from now but this year the trees are still barely budding.