What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Can water pump pressure be too high?

bp71k5

bp71k5

3/4 ton status
Joined
Mar 31, 2006
Posts
8,840
Reaction score
2,833
Location
Knoxville, TN 37922
I replaced my third radiator today. The first two were griffin aluminum and I was told they were damaged by some unknown mounting problem. So I have up and got an oriellys copper/brass radiator which has been working fine for 5 months. Then yesterday I see a small leak puddling on the driveway and when I start it this afternoon to find the leak, it's gotten much bigger and I can easily spot it spraying from a joint between the side tank and the cooling fins.

So my question is whether there's some other issue going on with the cooling system? Could my water pump be pressurizing the system too high? I've replaced the radiator cap (16lb cap) so I've been assuming that wasn't possible, but I'm about out of ideas. Any other things to look for?

Here's a picture of the leak since everyone likes pictures...
 
Water pumps on a closed system do not build presure in the radiator. A small amount of presure will be present in the block when the engine is cold and the thermostat is closed. Presure is built by heat. If you are running a good cap, it should release the pressure when it gets too high.
 
That's what I assumed to be true. Unless parts store caps are normally bad, it must be something else. I ordered a new stant cap today, just in case. The radiator comes with a lifetime warranty, but if I can't rely on the thing to last more than 6 months of freeway use, I'm even more hesitant to bring it to Moab this summer.
 
Is the core support straight? I saw a slightly twisted one eat radiators. If you set the radiator in the bottom supports, do the tops line up with no issues?
 
The core support doesn't appear to be tweaked, and I custom made the top mounts so they line up with the top pretty well and the radiator sits pretty square in the mounts. I could add some spacers under the top mounts to let the radiator wiggle around a little bit.
 
Why did you have to make custom upper mounts? It looks like you are using the rubber on the mounts, right?
 
ktmoutfront said:
Why did you have to make custom upper mounts? It looks like you are using the rubber on the mounts, right?
Click to expand...

The truck came stock with a 3 core radiator and all the 4 cores I've been using seem to be about 1/4"-1/2" taller. The 3 core mounts seemed to squeeze the bigger radiator too much and caused a leak (at least that's what they told me).

So I just made taller upper mounts that hold the top of the radiator in place without squeezing downward. The rubber is in place on all 4 corners.

The leak that popped up is just in the middle of the side tank and looks like the solder joint just failed. Not sure why it would fail so catastrophically after 5 months.

One detail I remember about electrolysis on the aluminum radiators, but I've not heard of any problem with brass versions, unless the solder is susceptible to it. Maybe Ill try to ground the radiator.
 
Bad radiator. Even the new brass ones are inferior. I got lucky with the Jimmy. Found an original 4 row, had it rebuilt. 9 years ago.
 
AJs72K5 said:
Is the overflow plugged?
Click to expand...

Nope, the overflow tank was getting lower and higher with engine temperature up until yesterday.

I'm a little worried about Wades question about core support maybe causing a problem. The tires are at highway pressure and so the thing acts like it has no suspension sometimes. Maybe I should find a way to reinforce the core support just in case...
 
ktmoutfront said:
Bad radiator. Even the new brass ones are inferior. I got lucky with the Jimmy. Found an original 4 row, had it rebuilt. 9 years ago.
Click to expand...

That's what I'd normally assume, if i hadn't had so many problem. Maybe if the replacement starts leaking ill take it to a shop and have them build me a tougher version.
 
Are your body mounts under the core support thrashed? If something is moving, that may be part of the issue. You should be able to see clean metal at the seams on the support if it is moving. The one I was dwaling with had been hit. Not bad enough to be noticeable. Until I checked diagonal measurements at the mounts. It was out of square by 3/4". Tightened the radiator down and it would start leaking later.
 
The bushings are poly and so a decent, but I had been driving with the bolts loosened for a while while I was working on the cage plates. I wonder if that may have done it. I just tightened the bolts back up a few weeks ago.
 
It's california, we don't have any money for street repair and so it's a little like driving around a mine field of pot holes, speed bumps, and wacky pavement patches that jar the heck out of the front end. I'll check for square though tomorrow and see what it's like. Thanks for the tips.
 
70jimmy said:
Did you change from 3 row brackets on the bottom to 4 row? You can order the brackets from LMC. That is what I did when I swapped to 4 core.
Click to expand...

Yea, I swapped them out. They are similar but just a little longer if I remember right.
 
A bad head gasket can cause excessive pressure in the cooling system.
Take the cap off and let it warm up till the thermo opens and watch for little air bubbles. Also running straight unmixed antifreeze will cause problems but usually it will burn up the pump.
 
You must log in or register to reply here.

Latest Posts

Top Bottom