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Loosing Coolant Underneath Engine

December 16, 2020, 09:33:15 pm

Departed MOT last week and drove to El Paso ( ~ 800 miles) in two days, stopping in Eldorado overnight.  While at MOT I had the coolant filter changed among other misc. maintenance items.  It's been below freezing here in El Paso the past couple of days.  Yesterday I noticed a puddle about a foot in circumference underneath the engine and after investigating noted the liquid was coolant.  Checked the radiator overflow tank and it was empty.  It appears to be leaking from around the area of the water pump (see pictures).  I tried tightening the bolts, but they would not budge.  Had a leak similar to this in the summer of 2018 in Palo Duro Canyon SP.  Poured some more coolant in the overflow  reservoir and motored on.  Leak stopped by itself.  Not a problem that I know of until now.  Was loosing some coolant underneath the radiator in June 2019; FOT tightened the bolts connecting the  core to the tanks and put in some Bar's and that solved that problem.  Do I have a failing water pump or is something else going on?  Please advise. 

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Re: Loosing Coolant Underneath Engine

Reply #1 – December 16, 2020, 10:04:48 pm

I looked at an ISM pump online.  It, and the photos you posted look familiar to me.  I have a coolant leak on my M-11.  The pump has a weep hole.  If the coolant is coming out of the weep hole, the pump is failed.  If there is mineral-looking deposits only, it is probably OK.

On mine, the curved horn of the water pump fits into a fitting attached to the block.  There is an o-ring between.  On mine, the o-ring is leaking, and dripping down to the bolts shown in your photos.

Tomorrow, I am taking a wrench to mine to fix it.  Waiting on the o-ring to come.

Spray the area liberally with brake cleaner.  It will flush away the coolant and then quickly dry, so you can really see where the drip is coming from.

I hope this helps.  No doubt a forum member with more relevant experience will chime in.

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Re: Loosing Coolant Underneath Engine

Reply #2 – December 16, 2020, 10:16:23 pm

I would try loosing the bolts to see if they are seized. Be careful and not break the bolts. If you can remove the bolts clean the
threads and apply never seize to the threads and then tighten them up. Only do one bolt at a time. As I was posting another member
posted and I thought it was a gasket was leaking but with an O ring it will probably need to be change. If it is only leaking out the
bolts you might get away by wrapping some Teflon tape around the head of the bolt to help seal it to get somewhere where you
can fix it properly.

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Re: Loosing Coolant Underneath Engine

Reply #3 – December 17, 2020, 07:40:51 pm

Thanks for the replies.  El Paso has a Cummins repair facility.  Will be taking the rig there for a new engine water pump and thermostat.  Estimate is 2 1/2 coach bucks.  May get it done as early as tomorrow, most likely it will be Monday.  Could have used the money to buy a new MacBook Pro 

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