HD4 coolant foaming over issue

Hi all,

I'm having an unfortunate issue with my HD4 again and I'm afraid I've really done something terrible to the old girl. I hope I'm wrong.

I'm up in Canada and we had a good extended cold snap back in Nov/Dec where the temps were down to -25 C (around -13 F) for extended periods. I used my machine for some digging work along a creek since the banks were nice and frozen, and I figured a machine like this could handle working in that kind of cold as long as I let her warm up long enough before getting to it.

Well, I used her a few times in these temps for some HARD work, and things were fine... I probably did about 3 sessions with no apparent problems or issues with the machine. On the last time I used it for that though, I did notice some coolant drips along the trail after I drove it back up and parked it. I just figured it was a bit of overflow though since I had been working her hard. I should note here that unfortunately my water/coolant temperature gauge is non-functional... I have a new one one the way!

Cut to a few days later, it was still bitterly cold and we had some snow, and I needed to clear some of it and I decided to use the machine to pile it up into a big pile. I managed to get her started and allowed her to idle/warm up a few minutes like usual, and then got to moving snow.

Now I figure the snow moving isn't nearly as hard on the machine as the digging work I was doing, and yet I wasn't half way done the job when all of a sudden a bunch of foam started coming out the radiator cap and was spraying everywhere due to dripping down and getting blown hard by the fan. I quickly took a look and it was just pouring out the overflow tube and foaming out the cap.

Needless to say I moved as quickly as I could to park the machine under cover in the shed and shut her down.

I've been working on her ever since trying to diagnose the problem and what I can do about it. Of course my immediate fear was a cracked block due to the cold (maybe I hadn't let her warm up enough?) or a blown head gasket.

Here's all the things I've done/checked so far.

I've checked the oilpan and there's no sign of any water/coolant in the oil... whew!

I've also taken apart the thermostat and checked to ensure it's still working as intended, and it's fine. There was a lot of rust in the thermostat and pipes though, so I completely drained and flushed the system and ran Prestone cooling system flush/cleaner TWICE, and gave the system a good flush with water multiple times and in between cleaner flushes, and refilled with fresh coolant (this is all happening after the cold snap now by the way, temps are above freezing by a few degrees).

After doing all that I started her up again to see if she'd still foam out the radiator cap and it looks like she is unfortunately... but not right away. It takes like 10-15 minutes of warm-up/medium idle until the foaming starts to show up. But I also know now that the system isn't overheating because I have an IR thermometer and the block is getting nowhere even close to overheated (less than 200 F).

So now I'm left wondering if I have a blown head gasket. But it's weird to me because I would think if that was the case bubbles/foam would appear pretty much immediately upon start up, no? But what I find is that the foaming doesn't happen until after a significant amount of warm-up/idling (10-15 minutes as mentioned above).

I've taken a video of the symptoms and I'm hoping to get some insight. I'm no mechanic so I'm not sure if what I'm seeing is "obvious" indication of a blown head gasket (or something else). It's also weird to me how it appears to expand and flow out the overflow, and then it'll really bubble and the level will drop, but then it'll rise up again and flow out the overflow steady, until another bubble and level drop. If it was a blown head gasket, wouldn't the bubbling be constant instead of sporadic like this?

As always help is much appreciated!

YouTube video here:

https://youtu.be/KCKUQTiXYqo

And here's what happens upon shut-down:


Edited by Daelric - 29 Jan 2022 at 12:06pm

Also, please consider checking the head for cracks.  

Hi Orangeman,

So I did the test in your link and after shaking the bottle, the foam/bubbles stayed for a lot longer than a minute. Here's a pic taken after 10 minutes of it sitting:

Alright gents, I could still use your help.

I ordered one of those block test kits and waited patiently for it to come in and it finally did today. I did up the old girl and she still wants to foam up a fair amount, even though the temps are still quite low.

I did the test and to my great surprise, it stayed blue. I thought for sure it wound be a positive test for combustion gasses.

I'm at a bit of a loss at this point. The coolant shake test Orangeman linked to certainly seems to indicate coolant contamination of some sort, but if its not combustion gasses and there's no water /coolant in the oil, what could it be? Is it possible for a head gasket to be blown and allow oil into the coolant with no combustion gas present?

Yea it works for diesels, says right in the instructions that while it should turn yellow for gasoline engines if there's a leak, for diesels it might be more of a greenish colour.

i would agree it might be your water pump. i had to replace mine. 190 is the same

A gasket is inexpensive. Pull your pump from the engine and get a look. Probably not an expensive part to replace or rebuild. I've had several pumps rebuilt by a company going by waterpumpkits.com and they've all been reasonable in price and have replacement castings for just about anything out there I've found.

Ok, I've pulled the water pump off but I'm not 100% sure what I'm looking for here.

The water pump shaft seal COULD be drawing in air and causing your problem. If there is no overheating (a working temp gauge ??) I might just replace the pump and get on with life. If you'd tie a gallon milk jug on the radiator overflow tube and actually catch what is being vomited out, maybe you are simply overfilling the radiator  !!!   You cannot have the radiator clear full when cold....must be down at least 2 quarts from full, maybe 3 quarts.  If the vomiting never stops and you get to a gallon or even more, you must be getting compression into the coolant when working the engine. There are test strips to verify this scenario.

I was wondering about the water pump, myself.  It would seem to me that if it would suck air from somewnere, wouldn't it also leak coolant at the same site?  Anyway, at minimum, now that you have the pump out, get a rebuild kit, clean it up get the corrosion and crud off of the pump vanes, and re-assrmble.  It might also be possible that you didn't get all of the flush stuf out, especially if there may be crud deposits that hold some fluid in...

Alright I decided to order a new water pump. Hopefully it wont take too long to get here. In the meantime, I'm going to flush out the system with more of that coolant system flush/cleaner stuff and then give it a REALLY thorough rinse out with fresh water.

I'll be in touch to let you all know how it turns out.

DrAllis wrote: You know, a couple of years ago, I had a Cat C-9 engine on a dredge pump that we wound up having the radiator core replaced first (blocked tubes with rust and then the engine replaced with a long block (block/cyl head passages also plugged). Radiator was not getting coolant flow thru it properly. Upper hose was always COLD.  Lower hose became hot from the hot water in the block backing up. Took about 30 minutes at full throttle on a summer day. to get to 200F. This was all due to not using antifreeze in the summer and draining it for the winter months. Rust everywhere.  Using a heat gun, the lower parts of the block (where coolant was) would get warmer and warmer, while the cylinder head seemed to gain little to no heat at all. Anyway, after as much diagnosis as could be done WITHOUT a tear down of the engine (that had 9,000 hrs on it) the reman long-block was installed and everything was fine after that, BUT the radiator was repaired first as it was blocked badly internally. My theory was the small vertical passages thru the blocks upper deck and the bottom of the cylinder head were so plugged, the coolant wasn't able to flow correctly.  The "norm" for the A-C 2000 series engine is this-----in cold weather, like 30 degrees F and less, you have a hard time for them to ever get to 180 degrees, even when working them and even with the radiator covered with cardboard. They do NOT run warm when ambient temps are cool. They just don't.

The thing that I don't understand, is that if all this is the case, then what does it even matter if the system isn't working 100% "properly"? Because while what you write sounds bad (blockages in radiator etc), if it's not running up into damaging temps, then what's the harm?

Thank you for reporting back with your findings, and status or your repairs. It is quite annoying to attempt to help a party with troubles, and they don't follow up with closure; only to show up with the next problem.