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Coolant Pressure Issue.


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Check the air compressor.

I had a E7 427 that was puking coolant & overheating, turned out that there was a crack in the air compressor allowing air pressure into the cooling system.

Also, this past week where I work now, we had a Cat c13 in a IH Paystar blowing coolant out so bad it ruptured the reservoir tank. Turned out to be a blown head gasket in the air compressor.

I thought air compressor at first as well. I had a Cummins in a sterling that had a bad compressor head gasket and it pumped air into the coolant. You would smell coolant in the air tanks and it would be warm air coming out the lines. I opened the tanks on the Mack and let the compressor continue to pump, but I couldn't replicate the problem. Also any water that built up in the air tanks was clean and ice cold no matter what the temp the engine was so that made me look elsewhere for the issue. I ran it hard on the NJ turnpike for 10 miles and it didn't build pressure like before. I also routed the overflow tube where I can see it without opening the hood each time I came to a stop. So far no issues, but if it does start to pump up again, I plan on pulling the EGR off the engine and give it a full inspection.

One odd thing I noticed, When the waterpump let go I replaced the pump along with a new Fleetguard water filter. Not soon after the swap I started having issues. When I pulled out the oil cooler filter I saw little grains of the element that's inside of the water filter in the screen. Normally they shouldn't escape the filter and get into the coolant. At least I've never seen that before on any engine's cooling system I've worked on. After replacing the double tank with the single tank, I also replaced the water filter again as a safe guard along with new coolant. Now I'm wondering if a defective water filter was the cause of my problems to begin with. I tried filling up the filter I took off the engine with water along side a brand new water filter and it seems to fill up slower then the new filter, I filled the middle and it don't go down and fill the outer passage of the filter as fast as the new one so it's making me suspect that it was building pressure due to the blockage inside the filter. :unsure:

Bad filters are very uncommon so I'm just curious if I won the unlucky lotto in this situation. Anyone ever experience a defective filter before?

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I thought air compressor at first as well. I had a Cummins in a sterling that had a bad compressor head gasket and it pumped air into the coolant. You would smell coolant in the air tanks and it would be warm air coming out the lines. I opened the tanks on the Mack and let the compressor continue to pump, but I couldn't replicate the problem. Also any water that built up in the air tanks was clean and ice cold no matter what the temp the engine was so that made me look elsewhere for the issue. I ran it hard on the NJ turnpike for 10 miles and it didn't build pressure like before. I also routed the overflow tube where I can see it without opening the hood each time I came to a stop. So far no issues, but if it does start to pump up again, I plan on pulling the EGR off the engine and give it a full inspection.

One odd thing I noticed, When the waterpump let go I replaced the pump along with a new Fleetguard water filter. Not soon after the swap I started having issues. When I pulled out the oil cooler filter I saw little grains of the element that's inside of the water filter in the screen. Normally they shouldn't escape the filter and get into the coolant. At least I've never seen that before on any engine's cooling system I've worked on. After replacing the double tank with the single tank, I also replaced the water filter again as a safe guard along with new coolant. Now I'm wondering if a defective water filter was the cause of my problems to begin with. I tried filling up the filter I took off the engine with water along side a brand new water filter and it seems to fill up slower then the new filter, I filled the middle and it don't go down and fill the outer passage of the filter as fast as the new one so it's making me suspect that it was building pressure due to the blockage inside the filter. :unsure:

Bad filters are very uncommon so I'm just curious if I won the unlucky lotto in this situation. Anyone ever experience a defective filter before?

It seems like I remember Cummins having some kind of recall or an issue of some kind with their oil filters plugging because of the filter media not too long back.

"Mebbe I'm too ugly and stupid to give up!"

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Happy to announce that the truck has been trouble free so far and I've been running the hell out of it with a drop of coolant loss.

Thanks again guys for your help! I would have never figured a TSB for a problem that has no actual reason behind it.

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we had a truck like this and after a bunch of times we finally got the egr cooler to leak it would only leak sometimes

This is my next step. I replaced the waterpump and even pulled it back out to check to be sure it wasn't slipping on the shaft.

I took the truck to Albany the other day and it blew coolant out the overflow tube once again even with the one piece tank. :angry:

I bled the air out and filled the tank again and it got me home without any issue. The next day I took it upstate NY with a load and it pumped coolant out again. I bled the air and refilled it, but it blew out again in a short while. I checked the coolant its a tinge darker and has a slight exhaust smell to it. I called Mack and the service manager told me that they been changing the EGR coolers for these issues. Then he quoted me a price of $1500 for it! I pulled it off the engine this afternoon, but a little unsure what the best way to test it would be. I didn't see any coolant in the exhaust inlet or outlet, but it probably burned off anyways so how exactly can I test this before I throw more money at it without being 100% sure?

Thanks for any info.

For those keeping score....

Replaced and then re-checked waterpump. (No issues)

Replaced both thermostats.

Pulled out radiator and checked for blockage. (Nothing inside, no blockage)

Checked oil cooler filter (Clean and clear)

Replaced the 2 piece reservoir with the updated one piece (Didn't solve issue)

Flushed coolant twice

Replaced water filter twice

No oil in coolant

No coolant in oil

No smoke

Let air compressor pump but didn't replicate problem.

Now I pulled the EGR cooler off and plan to test it to be 100% sure. There was a hand engraved etching on the back with the date 12/Nov/2003 and Made in Mexico. I have 298K miles on the truck and this is the original cooler so its very possible that this may be the issue.

Now how do I test it???

Edited by Astoria Mechanic
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I don't have a copy of the bulletin, but here are the instructions from it.

Pressure test the EGR cooler as follows:

Operate the vehicle until normal operating temperature is obtained.

The engine must be at operating temperature to perform this test. If the engine is not at operating temperature, results of this test will be inconclusive.

Return to the service facility, shut the engine off and apply the parking brakes.

Open the hood and then remove the top halves of both the upper and lower clamps that secure the mass flow tube to the engine.

Disconnect the mass flow tube coupling hose from the EGR cooler, and move the tube out of the way. If the EGR cooler utilizes the flange adapter hose connection, remove the V-band clamp from the adapter to disconnect the mass flow tube from the cooler.

Remove the cap from the surge tank.

Install the EGR cooler test fixture to the cooler.

Fully close the test fixture air regulator before connecting shop air.

post-6084-0-62078000-1304646930_thumb.jp

Connect shop air to the regulator fitting, and then slowly open the regulator until a maximum of 20 psi (as indicated on the pressure gauge) is applied.

DO NOT apply more than 20 psi to the EGR cooler.

With air pressure applied to the EGR cooler, observe the coolant surge tank. If the EGR cooler is leaking internally, a gurgling sound will be heard coming from the surge tank, and coolant will eventually be pushed out through the surge tank filler neck as the coolant aerates. Replace the EGR cooler if the results of this test indicate that the EGR cooler is leaking internally.

If the pushing coolant complaint cannot be resolved after performing the investigation outlined above, the cause may be combustion leakage past the head gasket and/or fire rings. Diagnostic procedures to determine combustion leakage are outlined in service bulletin SB213042. Combustion leakage, however, is the least likely cause of pushing coolant.

"Mebbe I'm too ugly and stupid to give up!"

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I don't have a copy of the bulletin, but here are the instructions from it.

Pressure test the EGR cooler as follows:

Operate the vehicle until normal operating temperature is obtained.

The engine must be at operating temperature to perform this test. If the engine is not at operating temperature, results of this test will be inconclusive.

Return to the service facility, shut the engine off and apply the parking brakes.

Open the hood and then remove the top halves of both the upper and lower clamps that secure the mass flow tube to the engine.

Disconnect the mass flow tube coupling hose from the EGR cooler, and move the tube out of the way. If the EGR cooler utilizes the flange adapter hose connection, remove the V-band clamp from the adapter to disconnect the mass flow tube from the cooler.

Remove the cap from the surge tank.

Install the EGR cooler test fixture to the cooler.

Fully close the test fixture air regulator before connecting shop air.

post-6084-0-62078000-1304646930_thumb.jp

Connect shop air to the regulator fitting, and then slowly open the regulator until a maximum of 20 psi (as indicated on the pressure gauge) is applied.

DO NOT apply more than 20 psi to the EGR cooler.

With air pressure applied to the EGR cooler, observe the coolant surge tank. If the EGR cooler is leaking internally, a gurgling sound will be heard coming from the surge tank, and coolant will eventually be pushed out through the surge tank filler neck as the coolant aerates. Replace the EGR cooler if the results of this test indicate that the EGR cooler is leaking internally.

If the pushing coolant complaint cannot be resolved after performing the investigation outlined above, the cause may be combustion leakage past the head gasket and/or fire rings. Diagnostic procedures to determine combustion leakage are outlined in service bulletin SB213042. Combustion leakage, however, is the least likely cause of pushing coolant.

Thank you sir. I knew there had to be some sort of tool to perform this. Im also glad to hear that the head gasket is the least likely issue for this problem.

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The EGR cooler has been confirmed cracked internally. Its good that its not a head gasket, but sucks that it costs $1500! Even the Mack parts dealer was shocked at the cost of these things. I tried to see if he could work out a lower price since we been dealing with them for almost 35 years now and he said that price is the best he can do. I'll have the part on Monday and installed some point during the week. The Mack service manager said that they are releasing a updated computer tune in the very near future that's supposed to prevent this from happening again. He has a tractor with the same exact problems in his shop this very moment and they are waiting for the update to try out on it. I didn't get all the details, but they told us to bring the tractor by when its available. Ill be sure to find out what exactly it does to prevent this problem.

Thanks for the info gentlemen, I'm hoping this ends my headache!

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  • 10 months later...

Hi, i apologise for bumping this but i have a similar problem.

could someone please tell me if the 1999 EA7-435 has the oil cooler screen you're refering to ?

I ask because there is a "T" type affair where the "Y" pipe should be. This "T" consists of the pipe from the lower radiator to the oil cooler, and half way along this pipe is where the top expansion tank hose plumbs in to make the "T".

It has a spin on water filter beside the thermostat housing but it does not have the external EGR.

post-7355-0-75907300-1332305450.jpg

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  • 3 years later...
  • 1 year later...

I have the same problem now with my 1997 ch613, I got an E7 355 and it's pushing coolant  to the overflow tank but it's not retrieving it, i notice that when the bottom  tank gets full and the fan clutch kicks in, the coolant gets sucked back up to the top tank and that's when it cools normal, but now it's not doing it and it's pushing coolant off the bottom tank cap until the alarm turns on and shut off the truck, it doesn't get hot it's just low on water. I've try almos everything 

change water filter, change top tank, change most of the main hoses, new gaskets on air compressor, took off  water pump and its good, oil cooler is clean, radiator got clean twice now. What else can I do? We did some test to check head gaskets but we didn't find any carbon monoxide . I can run 100 miles before alarm is on. 

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Did you replace the two piece plastic expansion tank with the one piece metal expansion tank?   Years ago Mack issued a service bulletin about problems with the plastic tanks.  

Denny

330-550-6020

A "Mack Pack" Charter Member

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I told the mack salesman about it and he told me they didn't have the one for my engine, they only had the 16psi, and he said that I needed the 10psi but he was not sure if there is one for this Truck. Is it the same one for all of this models? 

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  • 3 years later...

Hello there, I'm new to the Forum. I hope I'm not barging in on a conversation at the wrong topic. I've recently got my front water pump housing tore down to replace with a new one, and a lot of the bolts seemed extremely hard coming out of the front cover - two of them were broken (fan hub bracket studs). Can anybody tell me if Mack recommends anti-seize on any of the accessory bolts in this cover?

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