81 wagoneer water pump

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81 wagoneer water pump

Post by Fbnella » Sun Feb 21, 2021 10:35 am

My 81 Wagoneer Limited has been sitting off/on for the last 4 years. I rarely drive it because it is always a royal PITA to start after it sits for more than 7-10 days. So I saved up and bought the fi-tech efi with force fuel kit for it a few weeks back. First off, it runs like a dream. I've never heard it idle so well and it starts on the first crank every time. Now on to my problem, I'm suddenly overheating like crazy. I decided to put it in 4-wheel drive and take it for a spin in the snow and just break it in a little after sitting for so long. And I came home about 10 minutes later to steam coming out of the water pump. Radiator and fan were replaced about 500 miles ago so I'm pretty sure that's not the culprit. Water temp was 225 degrees by the fi-tech control panel reading when I shut it down in the driveway. Is the water pump my most likely candidate and is this something I can do on my own? I had someone come install the fi-tech for me, so my funds are pretty low at this point. I wasn't comfortable dealing with the fuel lines, but I feel like I can handle the water pump. Any pit falls to look out for if I take this on?

Here's the link to my overheating.


Any help would be greatly appreciated.

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Re: 81 wagoneer water pump

Post by Stuka » Sun Feb 21, 2021 2:10 pm

Its hard to tell in the video, was the steam coming from one of the coolant lines that goes into the water pump, or was it coming out around the shaft?

If its one of the lines, thats a very easy fix. If its coming out around the shaft, or the weephole, then you have to change the water pump. Which an an AMC V8 is pretty easy. I would advise changing the coolant lines at the same time.

It can be done with basic hand tools. I would advise using high-tack ( https://www.amazon.com/Permatex-80062-H ... B000HBGHB8 ) over RTV for the paper gasket as it seals much better. Be sure to clean the gasket surface on the timing cover well.

There are instructions for the water pump here (Note, this covers several engines, be sure to look at the page foe the V8s): https://oljeep.com/gw/81_tsm/1c.pdf

When refilling the coolant, be sure to use a 50:50 mix with water, or buy premixed coolant. And, you will need to 'burp' the system. When you first fill it up, you will need to run the engine to get the air out, and fill it up again. This may take several cycles.
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Re: 81 wagoneer water pump

Post by letank » Sun Feb 21, 2021 6:56 pm

10 min... and steaming in the snow... yes the water pump is steaming... I could suspect the thermostat not opening and the pressure blowing the water pump....

If you can rent a coolant pressure testing kit, Autozone or Oreillys have them, not too sure of your area. Pressure testing the system with some liquid in the system could help you diagnose the real area of leakage. Test to 5 or 8 psi is enough , the radiator cap is rated for 15psi.

the bolts have different length, use a piece of cardboard as a template to keep track or the order. With the AC it is a bit more challenging.

there is an aluminum version of our water pump that is nice, because the outside does not rust.. the GMB aluminum water pump, even Jeff Bezos sells it on the amazing web site


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74 wag (349 Kmiles... parked, next step is a rust free body)
85 Gwag (227 Kmiles... the running test lab)
See Engine bits , Fuel and brake lines, Body work, Trany and TC

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