My truck is having an over heating problem. Tonight when I parked it she was sitting at about 210-220, but that was after hitting 250 earlier. I turned off the engine and felt the radiator with my hand....the bottom half of the radiator was luke warm and I could have held it all night, but the top half of the radiator I could barely touch. Is this bad?

Also the top hose was too hot to hold and the botton hose was just warm.

Thoughts, comments???

Thanks,

Mike

 

sounds like the bottom half of your radiator is plugged up. that ain't good cuz you ain't gettin any circulation.

 

If the overheating just suddenly started it is most likely the thermostat or the belt failed on the water pump. After that the water pump could have failed, but that's unlikely as unless the impellor has come off the shaft it should still send coolant around the system.

It isn't likely to be a fan or air flow problem, otherwise the whole radiator would be hot.

If the overheating crept up on you, as well as checking the radiator as mentioned you need to check the temperature guage is reading OK, which isn't easy.

If you touched the top of the radiator it could have removed skin that is quite hazardous. Did you get any blisters? That's one way to check it.

 

Didn't get any blisters fortunantely!

I've since recored the radiator and replaced the lower hose with one with a spring. Thus far the entire cooling system has been replaced, except for the fan clutch which I'll replace with a thermal one to cure an unrelated concern.

I've since deduced that the driver side of the engine or head is the only part of the engine that is getting hot so quickly. The passenger side stays well within specs and even the temp sensor that is located in the intake manifold is giving reading acceptable temp readings. It's only temps on the driver side that are shooting way up. It's not the sending unit because I swapped sides/sending units and still got the same results. I have two sending units, one in each head for testing.

I'll check valve adjustment tomorrow and probably pull the intake manifold later this week.

I'll let you guys know what I find.

Mike

 

Ah ha! just the one side eh? Is it at all possible that the gasket blank in the inlet manifold has come out? If it is not in properly, the water can almost completely bypass the head on the V 8.

Or a bit of the bottom hose internal liner has come out and is obstructing the pump outlet on one side only.

 

Well, adjusting the valves last night didn't fix it.

Cool ideas. I'm not sure what part of the gasket you are talking when referring to the gasket blank. Hopefully I should have a new set of manifold gaskets to look at in a couple days.

When you mentioned the hose liner, did you mean that an actual chunk of the lower radiator hose may have started circulating with the water?

I'm hoping for the gasket problem since it is a pretty easy fix.

Oh, and adjusting the valves last night didn't fix it.

Thanks a bunch!!

 

Hi.
The manuals don't explain the inlet gasket properly. Also one gasket set I got was wrong, but the set from NAPA were good. And it depends on the engine year and model. So you need to read their instructions very carefully

But basically one end of the cooling outlet from each head gets blanked, to make sure the coolant flows the correct way through the heads, and doesn't bypass the circuit and go straight to the thermostat.

I can't remember if it is the front or back that needs blanking on some engines, but the manifold set instructions will say. Check when you take the old set out if they are the same both sides.

Some engines also need the exhaust gas recirc - yuk - route blanked or restricted. I think EGR stinks. but that's another story.

They use blanks because the heads can fit either bank of cylinders, so they have coolant outlets at both ends. One of them each bank therefore isn't needed.

The lower hoses can collapse if the cooling system is not properly pressurised, and in extreme cases with old hoses, the inner rubber can flex away from the hose and a chunk can get loose into the cooling system. The cooling pump has two outlets, so if one gets blocked, most of the flow will go to one side of the engine, leaving the other side overheating.

Good luck.

 

Anyone got a pic of this?? it might help. Im gonna pull my intake off this weekend and redo it. so if not Ill tke one when I do it.

 

Great idea!!

 

uh anyone?? a good manual pic or somthin?

 

The manuals don't show the flow route, and it may vary by engine and manifold arrangement, but any decent gasket set should have a full explaination in the instructions.

I oringinally had some cheap ones and they didn't have the info.

On my engine, the coolant flow is from front to rear of the block around the cylinders, then the coolant goes up into the head, where it needs to flow rear to front.

The heads have coolant outlets both ends, so they didn't have to be made left or right, which is a huge manufaturing pain if they were.

Some valley pans can take flow from either end of the heads, so they would need the rear inlets blanked, so that the coolant is forced to flow along the heads. If the coolant is not made to flow, it will still be in the head, but not at all as effective as when flowing.

 

Problem solved!

I replaced the water pump with a used one that we knew was good and now she works like a charm.

The brand new GMB water pump that I put on the engine when I dropped it into the truck, was bad. Don't know yet exactly what was wrong with the pump, but I'm going to tear it down and find out. I guess that's what I get for assuming a new item was good, oh well.

Of course I discovered all of the above after pulling the intake
manifold off and replacing every other part of the cooling system. The good out of this though is now I know the rest of the cooling system won't be failing anytime soon.

FYI, vortech heads use unrestricted gaskets on both front and rear. The gaskets work on either side of the intake manifold, they're identical. This also may be why you can't have a weak water pump. The TBI heads however, use restricted manifold gaskets in the rear.

Thanks a bunch for everyone's help, input, and suggestions!

Mike