m817 water pump, gasket or pump failure

[highsiera]

Evening all, let me preface this question by saying I have very little hands on experience with these big diesels. The m817 has developed a coolant leak at the top front of the block . It appears to be coming from the bottom of the water pump. Do these pumps "weep" when they are failing? My feeling is it's just the gasket, which is an inexpensive fix. Has anyone else experienced this with their NHC250? Brian

 

[dozer1]

I guess I would clean it up real good and try and determine where it is leaking (the best I could) . Then if the pump feels nice and smooth when you spin it, and has not slop or play, I would try the gasket. They are cheap (like 5 bucks surplus). Then if all goes well you wont have to do it all over again because it really was the pump. If you dont mind spending a little more money, look into an exchange pump and put er on. Good Luck...Dean

 

[Scrounger]

Brian the water pumps on the NHC 250 do leak when they are getting ready to fail, ask me how I know. If the gasket is leaking, the leak would be at the bottom of the ring that holds the pump in place. To replace the pump on these things is ridiculously easy to do; changing belts is the “hard” thing. To remove and replace/ reinstall a pump. First drain some coolant, five gallons should be enough. Loosen the six bolts on the ring around the pump. Using a screwdriver like item rotate the pump in the block to loosen the belt. Slip the belt off the front of the pump them remove the six bolts holding the ring on. There is a thin metal gasket that seals the pump with the block. Reinstall in reverse order, just remember to coat the metal gasket with anti-seize, snug the bolts just enough to tighten the belt and then finish tightening the bolts alternating around and in steps so the gasket is pressed evenly. And don’t forget the hit the grease fitting while you’re at it.

 

[highsiera]

thank you guys, i'm going to start with the gasket and see if that does it. Thanks for the steps Scrounger. it's leaking out the bottom of where the pump meets the block so. Really doesn't look to involved if it has to be done twice.

B

 

[Hasbeen]

highsiera,

If you have trouble finding a gasket let me know. The Cummins part number is 130240
but they`re getting hard to find in the commercial world. We still rebuild a commercial variant of your pump, and should have seals, shafts,impellers,bearings, etc.

Good Luck

Hasbeen

 

[highsiera]

found the part @ tnj murray, good part,good service shipped quickly. will report back midweek, with pics if I remember the camera this time. If your as HASBEEN, I might be a COULDBE?

 

[Hasbeen]

Good Luck !

Hasbeen

 

[highsiera]

Went up today to work on the M817 with my to do list. First job was to reinstall the muffler that I repaired in the shop at home, new grade 8 stainless bolts, nuts and washers, went smoothly. Next was to reinstall the heater and brackets, not too bad either. Then on to the leaking water pump/ pump gasket. Backed out the 6 bolts on the retainer ring. It took and interesting combination of socket/ extension to get them all out. Again pretty easy. Slipped a big driver in one of the pump slots to loosen the belt. A couple taps with the big hammer and the pump dropped out. I did dain about 4 gallons of antifreeze before I started by the way. The meeting surfaces were rag cleaned. I did spin the pump a bit and it spun smoothly, no wobble either. The new gasket got a coat of anti-seize as several of you recommend and everything got put back together and tightenned up. I will say the excess anti-seize oozed and got all over me and the front of the motor in the process of manuevering the pump back into place. Anyways, thanks as always for all the tips. Some pictures below. Would have had more, but my "assistant" had the day off.

 

[dozer1]

So that was the end of the leak? BTW Those stainless bolts are a nice touch on the muffler.

 

[highsiera]

Howdy Dozer! I honestly can't say exactly, the old gasket looked ok and the pump had no pittting on the gasket face, nor did the end of the block. The only think that seemed out of the ordinary was that the 2 bootom bolts on the retaining ring had a lot of build up on the threads. It seemed odd because it was on part of the threads that were in the block. If I hadn't been 2 hours from nowhere, I probably would have replaced them with new stainless grade 5s also. Instead I rotated the 2 best bolts to the bottom position, wire brushed the threads on the others and put them in the top positions. No leaks after a 30 minute shakeout drive today, but we'll keep and eye on it down the road.

I try to use good hardware for several reasons. You're never buying more than a couple at a time, so a couple bucks extra for stainless is no bigee. But honestly the main reason is, I usually expect to have to do things twice, having clean fastners to work with the second time around eases the aggrivation factor

 

[dozer1]

I try to use good hardware for several reasons. You're never buying more than a couple at a time, so a couple bucks extra for stainless is no bigee. But honestly the main reason is, I usually expect to have to do things twice, having clean fastners to work with the second time around eases the aggrivation factor

Good reasons. I have gotten into the habit of using never sieze on about everything out here on the farm. I will go to replace a bearing on an auger or something that I replaced 10 years ago and it comes off with ease. Just kinda brings a smile to the face thinking you did that 10 years ago.