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Coolant Leak in Cummins ISC


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After driving the coach for its yearly inspection, I noticed a small wet spot under the engine a couple days later. I did a cursory inspection when I changed the oil and filter, but saw no wet spot or drips on the bottom of the engine. 
 

A few days later the spot was still there. A more thorough inspection revealed I may have a leak in the valve for the SCA canister, the one you can shut off to replace the canister. 
 

Luckily, I have a new one in the box on the shelf. Anyone have any idea how much fluid I’m likely to lose changing out that valve?  

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I'd guess several gallons.  There's usually a coolant drain under there on the bottom side of the oil cooler housing, or drain from the radiator petcock if that's easier.  No need to drain it all, 3-4 gallons should get the coolant level below that valve, strain the coolant as you pour it back in.  It's just an O ring seal on that black plastic valve core, if you can get that out in one piece it's reusable.  They're commonly broken so somebody would want an intact one.  It's also not needed if you drain the coolant to change the filter, if you've swapped to OAT then you probably don't have to change the filter ever again. 

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One trick is to have someone hold a shop vacuum where your recovery tank cap is. They can regulate how much vacuum you need by allowing a little gap as needed.

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Posted (edited)
5 hours ago, Benjamin said:

I'd guess several gallons.  There's usually a coolant drain under there on the bottom side of the oil cooler housing, or drain from the radiator petcock if that's easier.  No need to drain it all, 3-4 gallons should get the coolant level below that valve, strain the coolant as you pour it back in.  It's just an O ring seal on that black plastic valve core, if you can get that out in one piece it's reusable.  They're commonly broken so somebody would want an intact one.  It's also not needed if you drain the coolant to change the filter, if you've swapped to OAT then you probably don't have to change the filter ever again. 

I'm not sure what o-ring you are talking about.  I have the whole housing and it comes with a metal gasket - its the new version with better valve handles.  I've used a blank coolant filter (Fleetguard WF2122) since since I switched to OAT coolant over ten years ago. Here's a picture of the where the leak falls on the ground. I was wondering about reusing the coolant since its only a few years old. I can strain it with a paint strainer and cheesecloth before putting it back into the engine.

 

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Edited by dennis.mcdonaugh
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Yes, the o rings are on the black plastic part to seal to the housing. 

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Yes, if you can pull the shaft valve out in one piece. Depending on the engine, it could be made of two pieces held together by a screw. This is a breakdown for my ISM, for illustration. The shaft by itself is pricy so I don't even use it, it does not leak that much for just a filter replacement. 

Screenshot_20240329_172345_Chrome.jpg

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23 hours ago, dennis.mcdonaugh said:

Anyone have any idea how much fluid I’m likely to lose changing out that valve?  

Not the same engine (isl), but I drained about 4 gal when rebuilding my coolant filter valve

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On 3/30/2024 at 9:03 AM, wamcneil said:

Not the same engine (isl), but I drained about 4 gal when rebuilding my coolant filter valve

Thanks

I’m still waiting on the new empty coolant filter to arrive. Why does the empty one cost double what one with SCAs cost?  In the meantime I’m spraying the bolts with Kroil every day in hopes that they all come out easily. 

I can get to 3 bolts from the bottom, but one I have to reach through the exhaust manifold from the top. That is the upper bolt next to the oil filter. The filter totally blocks it from below. 

If this leak had started a couple days earlier, I could have replaced it while the oil was drained from the engine. 

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There should not be much oil lost if you had to remove the oil filter to gain access, at least not on my engine since most all of it will be in the pan. Just as much as drained when you removed the filter for oil change.

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7 hours ago, Ivan K said:

There should not be much oil lost if you had to remove the oil filter to gain access, at least not on my engine since most all of it will be in the pan. Just as much as drained when you removed the filter for oil change.

Thanks, I didn't know that. Now I have to decide which is worse, wrestling the oil filter off or leaning over the bed frame to get that top bolt off.

On another note, the coolant valve has stopped leaking again, just like it did about 8 years ago when I bought the new one I have in the box.

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I received the blank coolant filter yesterday and decided to replace the coolant valve today. I had a plan, turn off the valve, remove the old filter, turn the valve on and let the coolant drain. Remove four bolts and the valve, replace with four new bolts and new valve, install the new filter and replace lost coolant.

Things went south after the first step. The filter was stuck and I broke my filter wrench trying to get it off. None of my other filter wrenches were big enough or they were too big to work so off to NAPA to get a replacement. The new one was more robust than the 40 year old wrench I broke so I was sure I'd have the filter off in no time. It was so tight I bent the filter and twisted the new wrench. Plan B was to just take the four bolts out with the filter still attached.

The valve is held on by four 24-year old M10 bolts so I was really worried about breaking one off. I think you'd have to take off the manifold and turbo to get a broken bolt out because there is no space there to get a drill in there.  I used a ratcheting gear wrench because they aren't very long so I couldn't put a lot of torque on the bolts. I still had to pull on them pretty hard, even after spraying them with Kroil every day since last Monday. I worked back and forth and sprayed them again and in the end they came out intact and I backed them out just enough so the coolant could drain into the big square tub I used to collect it. After an hour, I'd estimate two gallons have come out. 

I'm going to let it drain over night and put the new valve on tomorrow. 

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It’s not a fun job. I would up rebuilding mine twice because I didn’t check real good and left an old o-ring stuck down in the bore. Working with my head right up against the slobber tube. Took a lot of washing to get all the nasty black oil out of my hair. Ugh

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When you get the coolant filter housing removed from the engine, look at the coolant passages in the engine block. In the block of my ISC the passages were threaded 3/4 NPT. I installed a 3/4 inch pipe plug in each passage and deleted the coolant filter completely as I had also changed to OAT long life coolant, no SCA required and filtering not as necessary.

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Thanks for that info.  Cummins removed the filter on the C series sometime around 2010 ish, so they agreed that it was not needed with OAT coolant. 

Some may say that was cost cutting, cheapening, etc.  I bet a lot of RVers keep the filter, even though 100-200,000 miles isn't going to wear out a water pump like an over the road truck could in the old days.  Good to know the threads might be there for emergency use. 

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26 minutes ago, bekec1 said:

When you get the coolant filter housing removed from the engine, look at the coolant passages in the engine block. In the block of my ISC the passages were threaded 3/4 NPT. I installed a 3/4 inch pipe plug in each passage and deleted the coolant filter completely as I had also changed to OAT long life coolant, no SCA required and filtering not as necessary.

I’ve had mine turned off for years since I had a blank filter (no SCAs) anyway. Eliminating the housing would definitely have eliminated the possibility of the valve leaking. 

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I removed the valve assembly this morning. I can't see what was providing a seal between the engine block and the valve body. There's no sign of anything like the aluminum gasket the new one has or any type of sealant. You can see the two 3/4 NPT fittings that bekec1 mentioned a couple posts above. I think I'm going to  go the route he did and stick two plugs in those holes. I wish I'd known about that 10 or so years ago when I bought the new valve body.

 

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Thanks!  I Got it back on. What should I torque the bolts to?  The bolts threads are 12 mm with a 10 mm head. I looked up grade 8.8 bolts and it said 65 ft/lbs. I’m pretty sure they weren’t that tight. The next grade on the list was 5.6 and 28 lbs was specified for them. 

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49 minutes ago, dennis.mcdonaugh said:

Thanks!  I Got it back on. What should I torque the bolts to?  The bolts threads are 12 mm with a 10 mm head. I looked up grade 8.8 bolts and it said 65 ft/lbs. I’m pretty sure they weren’t that tight. The next grade on the list was 5.6 and 28 lbs was specified for them. 

My ISM procedure says 40 pounds.

Screenshot_20240408_122332_Samsung Notes.jpg

Edited by Ivan K
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1 minute ago, wamcneil said:

Eek. 40ftlb sounds like a lot of torque. I didn’t attempt to put a torque wrench on mine. 

I just snugged it down as much as I could with a 10 mm wrench. There's not much leverage available on a wrench that size.

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It looks like I didn't screw anything up and the leak is gone. I'm going to keep the old one and rebuild it in case the new one leaks down the road. Its unlikely I'll be the owner when that happens since it took 24 years for the original to fail, but you never know. Do you remove the shaft and o-rings by taking off the knob with the philips screw in it?

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