Coolant leak!

Topic: Coolant leak! (Read 1587 times) previous topic - next topic

Coolant leak!

December 15, 2020, 02:16:28 pm

Yesterday, I replaced my old SCA coolant with OAT, and used Brett's excellent instructions. (Third coach I have used his write-up and benefited from his guidance.) Anyway, I have a coolant leak today.

See the photo of the driver side of the engine. If I understand my anatomy correctly the block in the upper part of the photo is the thermostat housing. The pipe below it is the inlet for the water pump. Am I getting this right? I cleaned the area with brake cleaner, and the leak seems to be at the joint of the pipe, where the larger angled pipe appears to slip over the straight pipe attached to the block.

What type of seal is in there?

Is this a good candidate for Bar's Leaks? When sitting, the drip is about one per eight seconds. When idling, the drip is about one per 1-2 seconds.

The happy news is that I got the new Haldex dryer on this morning with no more trouble than smacking big wrenches with big hammers. It is tight in there!

Re: Coolant leak!

Reply #1 – December 15, 2020, 02:21:40 pm

That seal would probably be an O ring. What keeps the angled pipe from coming off? It must have support below to hold it. Any picture of that area?

Re: Coolant leak!

Reply #2 – December 15, 2020, 02:34:50 pm

I found this thread the second time I searched for M11 water pump, but not the first. ?? Anyway, it appears that a person removes two bolts that hold the small pipe to the block, and then three bolts that hold the pump to the "other big thing." Then the pump and the small pipe rotate as a unit before the small pipe is removed and the o-ring exposed.

I am wondering about all of this. It is hard to even SEE the bolts. I should check the three bolts for tightness.

Still wondering of the Bar's Leaks might do it.

m11 water pump

Re: Coolant leak!

Reply #3 – December 15, 2020, 02:42:32 pm

Sealers don't work very well with something that has movement. I haven't tried to seal an O ring with a sealer so can't help there. Have had good luck with gaskets and radiator header leaks.

Re: Coolant leak!

Reply #4 – December 15, 2020, 08:04:06 pm

So I have been thinking this through, and I think I am getting enlightenment toward two different directions.

First, going by the M11 repair manual. It looks like the water pump can be twisted outward without removing the water pump, or the belt pulley. Remove the two bolts (cap screws) that hold the water outlet to the block. Then remove the three bolts that hold the water pump in place. Absent any obstructions, it looks like the pump would then pivot outward, hopefully giving enough space to free the water outlet from the pump. The only things holding it in would be the o-ring and grime. I looked at the layout - alternator might have to come out, but that is simple. New o-ring, five bolts, refill and done.

Has anyone done this, or is able to confirm that it can be done.

Second, when I was hosing off the work area after the multiple flushes, including the one with the Fleetguard alkaline cleaner, I remember there being a lot of small dark brown fragments. It reminded me of the black stuff from my old engine bay insulation, but I had vacuumed that up. I remembered all of this while going through the work yesterday, wondering how flushing the cooling system could create a leak.

I think there was a leak before, and a PO treated the system with Bar's Leaks. The alkaline cleaner removed the Bar's, allowing the leak to restart.

What do you think? Which direction would you go?

As an aside... This morning I was weary from yesterday's big adventure and disheartened by the leak. Actually I found TWO leaks. The second one appeared to be coming from one of the CAC hose connections. My first analysis was that I had a massive failure of some sort, and the CAC was half-filled with coolant, and was leaking out. My second analysis was the correct one - the screw clamp at the bottom of the plastic overflow reservoir, directly above, needed another 1/4 turn.

I gotta be more optimistic!

Re: Coolant leak!

Reply #5 – December 15, 2020, 08:26:31 pm

Quote from: oldmattb – December 15, 2020, 08:04:06 pm

1. Has anyone done this,
2. able to confirm that it can be done.

Matt,
1. Yes
2. Yes it can be done BUT it is a lot harder than what you read in that paragraph. That makes it sound like it is a 15 min. job not the 4hr. job it is.
3. Take the alternator off is a big help.
4. If I was going that deep I would replace the thermostat and the "O" rings on the oil cooler as they are right there when you get that deep. Somewhere in the past I posted about those "O"rings and will see if i can find it.

Mike

Re: Coolant leak!

Reply #6 – December 15, 2020, 08:34:41 pm

Quote from: Pamela & Mike – December 15, 2020, 08:26:31 pm

Matt,
1. Yes
2. Yes it can be done BUT it is a lot harder than what you read in that paragraph. That makes it sound like it is a 15 min. job not the 4hr. job it is.
3. Take the alternator off is a big help.
4. If I was going that deep I would replace the thermostat and the "O" rings on the oil cooler as they are right there when you get that deep. Somewhere in the past I posted about those "O"rings and will see if i can find it.

Mike

I know it would not be a quick job. My thought was about half a day to a day - I can see spending 45 minutes on getting a bolt to start in its hole. Not like you can eyeball it to line it up. Gotta get the coolant out and back in too!

Good advice on the thermostat and o-rings, though that might be for another time. Those might be a good project for summer, when it is too hot to travel! On the other hand, I think I have a seep from around there.

Re: Coolant leak!

Reply #7 – December 15, 2020, 08:35:44 pm

Matt, On mine that O ring would only leak when it was cold, but I couldn't stand to see that puddle underneath. I'll try to post pics of the parts diagram and the Cummins Invoice for parts. I changed out the thermostat also. The old O ring was basically dry rotted and brittle.

Re: Coolant leak!

Reply #8 – December 15, 2020, 09:40:46 pm

Matt,

I looked around and couldn't find where I wrote up about the oil cooler "O" rings I did find a reference to them but that was all. The problem with working on that area is you are right up next to the frame rail with no room to work. If that engine was in a class 8 truck you can just tilt the hood and walk right up to the water pump and get after it. With this location you will end up doing part of the work from the bottom side and part from the rear.

Mike

Re: Coolant leak!

Reply #9 – December 16, 2020, 12:20:16 am

The brown residue was probably the Bar's leak. Cleaner does remove sealers put in the cooling system. The radiator header was leaking on my crane and Bar's leak stopped it. When I did a flush I would have to add a bottle back in the system to stop it from leaking again.

Re: Coolant leak!

Reply #10 – December 16, 2020, 09:17:15 am

Thanks all! The current mood is to replace the cooling o-ring, but undecided on the oil o-rings - I need to look at that job some more. The thermostat will be another time. I will probably get into it this weekend - my hands and back are still smarting from other projects. Long ago, I had this idea that RV systems were big, so there was plenty of room to work. I now know the reason for the variety of socket extensions, wobbles, pivoting ratchet handles, stubby wrenches, thin-wall sockets, ratcheting breaker bars, ratcheting box-end wrenches, inspection mirrors, magnet-on-sticks...

Cost of that o-ring ranges from $15 to fifty cents, depending on the source. I am guessing there is nothing magical about it.

We had planned to be on the road this weekend, but our intended destinations seem all filled up. Maybe a couple of day trips and we can take the coach after Christmas.

I will let you guys know how the project goes.

Re: Coolant leak!

Reply #11 – December 16, 2020, 09:35:32 am

If the picture in reply #7 is the O ring it is a silicon one and might be hard to find at a hardware store.

Re: Coolant leak!

Reply #12 – December 16, 2020, 09:50:10 am

Quote from: craneman – December 16, 2020, 09:35:32 am

If the picture in reply #7 is the O ring it is a silicon one and might be hard to find at a hardware store.

Good point! I just ordered the official Cummins part. Actually a bag of 10 for a decent price. I will share!

Re: Coolant leak!

Reply #13 – December 18, 2020, 09:26:49 am

If your actually going to remove the water pump I would seriously consider replacing it.

Re: Coolant leak!

Reply #14 – December 18, 2020, 10:42:18 am

Does anyone have the thermostat and gasket numbers handy?

Re: Coolant leak!

Reply #15 – December 18, 2020, 11:30:30 am

"In for a penny, in for a pound"...If your going that far, might consider replacing the non-silicon hoses as well.

Re: Coolant leak!

Reply #16 – December 18, 2020, 12:09:02 pm

Quote from: oldmattb – December 18, 2020, 10:42:18 am

Does anyone have the thermostat and gasket numbers handy?

Cummins 3076489 Thermostat 180° Cat 4w4794 for sale online | eBay

Re: Coolant leak!

Reply #17 – December 18, 2020, 01:22:50 pm

Cummins Part #'s...M11 1998

Thermostat 3076489 $71.33(Cummins price)
Seal, Thermostat. 186780. $17.42
Seal, Rectangular Ring. 3080770. $6.49

Re: Coolant leak!

Reply #18 – December 18, 2020, 01:26:23 pm

Here's a deal.

Cummins 180* Thermostat #3076489 (CT21-123-01) | eBay

Re: Coolant leak!

Reply #19 – December 18, 2020, 07:41:10 pm

Thanks for the numbers, guys! I was out and about all day, and your info allowed me to get the order in before the weekend. Maybe get it a couple of days earlier!

I have learned so far that the "five bolt theory" almost works. It frees the block fitting enough to spin, to wiggle, to shake, but about 1/8" shy of being released from captivity. The thermostat housing must come off so the fitting can go up and out. I will replace the thermostat since it will be exposed. The pump shows no signs of weeping, so I will give it some more time.

I ordered a replacement for one silicone hose I perforated while removing. I will check the other short hose. It looks like most of the hoses are silicone already.

Re: Coolant leak!

Reply #20 – December 18, 2020, 08:13:58 pm

Matt,

When you pull the thermostat housing you will find a orifice in there. It belongs in there.

Mike

Re: Coolant leak!

Reply #21 – December 18, 2020, 09:31:32 pm

Quote from: Pamela & Mike – December 18, 2020, 08:13:58 pm

Matt,

When you pull the thermostat housing you will find a orifice in there. It belongs in there.

Mike

Thanks!
I found it, and made note. It was in the 1 5/8" hose just below the pump. Looks like a silver dollar with a 1/4" hole in the center.

Re: Coolant leak!

Reply #22 – December 18, 2020, 09:47:03 pm

That is it make sure you put it back in where you found it. It is real important for proper cooling.

Mike

Re: Coolant leak!

Reply #23 – December 19, 2020, 10:23:39 am

Not sure on yours but the 8.3 has one hose with a spring inside that the new hose does not come with.

Re: Coolant leak!

Reply #24 – December 23, 2020, 03:06:31 am

How to change M11 ISM water pump.

https://youtu.be/shX1ZdfngGE

Mark

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