Do you have a proper fan shroud?

Has the coolant been properly maintained?

Corroded water pump vanes, or backing plate will degrade flow when you need it most.

 

I do have a shroud for the fan.

Since I'm in california my mechanic just tried putting in just distilled water with JB Super radiator cooler and cooling system protector and water pump lubricant.

Water pump is brand new.

That is why my mechanic is stumped on why it still overheats

 

Usually a fan clutch that fails will lock up, and you would see better cooling. You should know if it is engaging or not, because it will be nearly as loud as the fan on a semi, or sound like a jet taking off. No visual test, unless you can see if it is spinning faster or slower.

 

I'll have my mechanic recheck the fan clutch since I don't think the fan clutch is engaging because I just hear the normal sound of the engine not like the " sound of a jet taking off". Thanks for the info.

 

Did your mechanic replace the backing plate when he replaced the water pump?

 

I've seen fan clutches fail by NOT locking up. Spin the fan by hand when the engine is off and it should have a decent amount of resistance. It should not be able to make a full turn after you spin it by hand, it should stop almost immediately after you let go.

Since your engine can stay cool at highway speed but not when sitting still it is a problem of not moving enough air by the fan. You do not want to let the engine get above 240 degF because that is the temp where oil degrading begins. It's always hard to figure something out when you replace a part with one that is bad off the shelf. It doesn't happen very often so we rarely suspect the new part we installed.

Retarding the timing shortens the burn time in the cylinder and puts more heat out the exhaust. Advancing the timing lengthens the burn time and puts more heat into the engine.

Good luck!

 

I don't think he did. But doesn't that come automatically when you buy the pump? And would it make a difference if it was not replaced?

There is a resistance on the fan clutch when I spin it. My mechanic checked the timing and he said everything is good there. The problem is the "radiator shop" who replaced most of the parts is not the same shop as my mechanic, so I have to go back and forth to each shop for each issue. My mechanic does not want to touch anything that the radiator shop replaced since he did not replaced them.

 

I've never seen a pump come WITH the backing plate.
if it is heavily pitted or has holes in it, the new pump is pretty ineffective.

 

But if that's the case wouldn't it be overheating when in freeways also not just in traffic?

 

Your symptoms are that it overheats in traffic.
As if the fan were not moving enough air.
Try keeping the revs up while crawling along. (use a lower gear)
The engine is not really working harder, just spinning faster.
This means the pump will be circulating more coolant.
If this helps keep it cool then obviously the increased circulation is mitigating the problem.
What is your normal engine speed when on the highway?

 

When you say "keep the revs up" does this mean I have to put it in Neutral every time and rev it when in traffic?

When driving on highways my speed is anywhere from 60-75 mph

 

Your truck doesn't have "1, 2, 3, OD"?
Just shift into a lower gear.

"What is your *engine* speed?"
Do you have a tach or any idea of engine speed on the highway?
There are plenty of online gearing calculators you can use to figure rpm's with the information from your door tag.

 

I do have "1,2,3 and OD" but wouldn't it be bad to use those when not climbing up? Sorry don't really know much about engines ...Let's say I put it on 2 or 1 in traffic does that automatically rev the engine more? or do I have to step on the gas and rev it manually in a gear on traffic?

I don't have a tachometer so with the "gearing calculators" how do I use that?

BTW I appreciate your help on these.

 

So if you put it in '2' it will stay in second even if you are doing 50.
I don't know what you call traffic.
You're not moving at all for how long?

Look on the tag for your tire size and rear axle code.
I think e4od's have a .712:1 ratio in top
Plug in the numbers and you will have engine rpm at (whatever road speed you choose, 70?)

 

Traffic sometimes are slow crawl maybe 5-15 mph stop and go. And sometimes when not moving at all maybe between 2-5 min.

Regarding "looking for the axle code" where do I find that? Sorry really new at this.