CUCV Aluminum Radiator Problems, is it just me?

[NovacaineFix]

Okay all you CUCVer's out there who have replaced their stock original radiators with the new style aluminum with plastic side tanks.

I have been having a problem that seems to have stemmed from the point at which I replaced my original copper/brass radiator with a newer aluminum radiator with the plastic side tanks. I have replaced just about everything and it seems that I cannot go 3 months before something pops, mainly heater cores. Last night, on my way back from Los Angeles, popped my 4th heater core, had to do a by-pass this morning. I am just about stumped on this one and figured I would reach out to see if any others are having similar issues.

The replacement list is as follows:

• Radiator (twice, on 2nd one)
  
• heater cores (just lost my 4th one, last 2 were Sceptor branded, not sure if they are the same as the fuel can manufacturer)
  
• thermostat 195°
  
• hoses - upper, lower, both heater core hoses and by-pass hose
• water pump
• coolant 50/50 pre-mix (the water here is hard as stone, no way I'm putting that in my truck)
• Radiator cap - twice. 1st one was a 16 lb cap and always seems to over pressurize, using a 13 lb cap currently

I have checked the coolant system for exhaust gases suspecting a leaky head gasket, and have found nothing, checked both cold and hot.
I have checked for electrolysis and grounds, all the grounds are good, even added 1 just to be safe. The only thing that bugs me is I fill the radiator, purge all the air out, run it up to temperature, re-fill and check, then fill the overflow tank. Before long, the overflow tank will be overfilled and it just seems that the radiator will not pull it back in when needed. On my 1st radiator, I re-drilled the overflow hole on the filler neck to a larger size, thinking that the gasket on the cap may be covering the hole and not allowing coolant to pass. Nothing changes.

While driving back from the desert and passing through the mountains, I did notice that I had very little heat from the heater vents, barely warm. Was thinking that maybe, just maybe the radiator was cooling too well and not allowing the thermostat to open properly and the the coolant is running hot in the engine and over cooled by the radiator, similar to the reason why you have to put a winter guard on the front of your radiator in really cold winter temperatures. But obviously this is a little harder to verify.


Now just for some background, I was a auto-tech for over 10 years, held a ASE Status, but have not recertified for years due to I don't work in the auto field anymore. I say this, so you know that I know my way around a wrench and have some clue of what I'm doing.

My next step here is to just pull the heads and just replace the head gaskets but what bugs me is that I just don't have the evidence here to justify it with the exception of the overpressurization issue.

Any Ideas???

Here is a rundown of my repair posts:

1st radiator
More radiator
Water pump and hoses
Heater Core
Heater Core Again
And again
Over pressure
Checking for electrolysis
Adding a ground, just for ships & giggles

The saga continues...

 

[nyoffroad]

You use the word "pop" and "over pressure", does the heater core actually pop open as in blow up?
I wonder if you have some kind've blockage in the cooling system, the first thing that comes to mind is the lower radiator hose may be collapsing while driving. The lower hose has suction especially at high RPM's and should have a spring inside it to prevent collapse.
Just something to check, I don't know if that would cause a high pressure in the system, I'd be tempted to plumb in a pressure gauge in one of the heater hoses and know for sure.

 

[NovacaineFix]

Yes, popping is probably the best term that I would use, or splitting.


This is one of the 1st heater cores that split/popped, right at the seam between the hose connections. The other heater cores all have been core leaks between the fins where it meets the header.
I know what you are saying and yes, the lower hose can collapse if the spring inside of it is missing or corroded, mine was pretty much that way just before I replaced it. I failed to mention, that I completely flushed the cooling system before installing the new radiator, both with flush chemical and then water until clear, then removing the water, due to the hardness of the local water.

 

[cucvrus]

I am going to throw my hat in the ring. Just a thought. Have you considered over pressurization of the cooling system? Due to a faulty radiator cap has probably been ruled out. But what about a leak at the head gasket. I had my Mule leaking at a head gasket for about 6 years and it would make the upper radiator hose smell like a balloon. I knew it was head gasket related or cracked head but just kept nursing it along. Last spring I changed the heads/head gaskets and the problem has since gone.I ran this truck until it was puffing a slight steam trail out of the drivers side tailpipe. The radiator was always at full pressure and it would hold the pressure overnight. But that is my guess as to the problem that you are having. You may not get oil in your water or water in your oil. But you could have a cracked head or head gasket creating the over pressurization. It is not the end of the world for you. At least I hope not. It was an easy fix that I turned into a major overhaul at my choice. It did help me a few times to have an extra set of heads so I kept the down time to a minimum by having the extra set reworked at the machine shop and was able to turn out other trucks in a day or 2. Just and idea. Not positive proof. but wanted to share it. Good Luck have a great day.

 

[cucvrus]

While driving back from the desert and passing through the mountains, I did notice that I had very little heat from the heater vents, barely warm. Was thinking that maybe, just maybe the radiator was cooling too well and not allowing the thermostat to open properly and the the coolant is running hot in the engine and over cooled by the radiator, similar to the reason why you have to put a winter guard on the front of your radiator in really cold winter temperatures. But obviously this is a little harder to verify.


Now just for some background, I was a auto-tech for over 10 years, held a ASE Status, but have not recertified for years due to I don't work in the auto field anymore. I say this, so you know that I know my way around a wrench and have some clue of what I'm doing.

My next step here is to just pull the heads and just replace the head gaskets but what bugs me is that I just don't have the evidence here to justify it with the exception of the over pressurization issue.

I never read over your entire post. After I did you have described the exact symptoms that mine had for years and towards the end it did get so over pressurized that I put 2 clamps on the top hose at both ends. I think the time has come to get the heads checked out at a machine shop and replace the head gaskets. I knew what mine was from the onset but was buying time as I had so many other projects started. I think it may have cost me about $500. for everything. That is machine shop of the heads, gaskets,new head bolts, and servicing the entire cooling system with a new water pump,hoses and thermostat. Have it and ask if you nee help. Do replace the head bolts they are 1 use type torque to yield and the heads need to be checked by a competent machine shop or you are wasting your time. Good luck. Any questions ask I will be happy to help if I can. Have a great day.

 

[NovacaineFix]

Thanks for the info CUCVRUS, I think I was looking for validation and or a 2nd opinion before doing major surgery. I have a strong feeling that you are correct either about the heads/gaskets or both, since every other check I have done seems to have turned up nothing. The heads I cannot check unless they are off and both you and I know that.

ANd yes, the radiator cap has been changed out, twice. Currently running on a 13lb cap instead of the stock 16lb.

Well, I don't have anything to lose by doing the heads, I'll keep you guys updated.

 

[cpf240]

If you suspect the heads, you can either buy a kit, or take it to a shop and sniff the radiator for exhaust gasses. A shop could probably do a pressure test to see if the pressure is indeed too high.

 

[NovacaineFix]

Back when I was a tech, I used to have a pressure testing kit, I may go and buy another one, who knows.

I tested for exhaust gases in the cooling system with a fluid tester that changes from blue to green when exhaust gases are present, kind of like a smog sniffer.

Looks like this:


The green part was from me checking it by sniffing the exhaust pipe, just to make sure it was actually working.

Checked at the radiator cap filler cold, warm and at full temp after relieving the pressure from the cap. It may be that after the pressure is released from removing the cap, whatever gap or crack there was is now not there(??), thats what making this so much a PITA.

 

[richingalveston]

You replaced the water pump, is possible you got the wrong rotation.
just guessing cause it looks like you are covering all the bases.

 

[richingalveston]

One other thing is it is easy to check compression through the glow plugs. If you have a cylinder pressuring the coolant system it should show a compression difference.
Might try compression test to validate a leak.

 

[NovacaineFix]

You replaced the water pump, is possible you got the wrong rotation.
just guessing cause it looks like you are covering all the bases.

To tell you the truth, Not sure. I have faith in my parts guy that he got me the right one, been going to him for over 15 years.

I have a v-belt driven water pump and I believe they are clockwise rotation and the serpentine belt types are the reverse direction (counter-clockwise) like what you are describing, but I think they only came on the later vehicles. Not to say that one could get mixed up, it would probably be hard to tell the difference unless they were side by side since they don't have the pulley attached to them.
I will have to have him look up the later model and see what the part number is.

 

[cucvrus]

NovacaineFix I posted my heads/head gaskets on the Mule rebuild thread for you. I hope you find it helpful. I did it all on a tight budget at first and then I went crazy. i wanted to retain the good looks and do some remodeling of the entire vehicle. I still have it as work in progress. Good Luck and Have a great day.

 

[infidel got me]

My buddy had the same issue a few years ago. Never blew a heater core, but it would blow upper radiator hoses-- only when towing his boat or trailer. He replaced everything in his cooling system before just bittin the bullet and pulling the heads. It's not too bad of a job- should have it done in a weekend ( less machine shop time) Let us know what you find, and good luck!

 

[NovacaineFix]

NovacaineFix I posted my heads/head gaskets on the Mule rebuild thread for you. I hope you find it helpful. I did it all on a tight budget at first and then I went crazy. i wanted to retain the good looks and do some remodeling of the entire vehicle. I still have it as work in progress. Good Luck and Have a great day.

Appreciate that, I saw that post and was wondering if you had posted that for me, before reading this. Thanks, I really do appreciate it.

I took some time in between diagnosis to work on the 5-ton today, nothing major, just some touch up paint in places.

But I did breakdown and buy a coolant pressure tester from Horrendous Freight (aka Harbor Freight), which I recommend against anyone buying.

The most common type of fitting, you have to use an adapter to get it to work, it's like using an adapter for your foot to get it to fit your shoe if that makes any sense. very awkward to use, but it works.
WTH? is this crap>>>>
The design of this tester is wonky, the gage should be facing towards you, but maybe I'm just over-critical

The cooling system never got above 10 lbs and this was after almost an hour running, about 15 minutes were held at fast idle (1500-1700 rpm's) to get the T-stat to open.

I wound up changing out the T-stat just for ships and giggles, we'll see.

I have no problem pulling the heads and re-doing them, but I just don't want to do it if that's not the issue.

 

[rustystud]

I have seen heads cause this problem and also a vapor lock do it too. On one engine I had to open up a drain port on the back of the engine to get the coolant to flow out. What would happen is the area that was not getting coolant flow would super heat causing steam to build-up in the engine. This steam would find it's way to the radiator (weakest link) and blow out the seams.
I'm not saying this is your problem and I think you need to do a compression check and cylinder leak-down test first as the heads are usually the prime culprit. If the heads check out then you should get a cheap "infrared gun" and with the engine hot start going over it checking for super hot spots.
Just a reminder, make sure the engine is hot before doing the compression and leak down tests as the cracks will be open then if there is any cracks in the heads.