Over heating engine issue???

[MaO3]

Hi Guys
My son has an older model Chev Truck that has had a engine replacement. He's having a issue with the heat gauge going into the Hot zone or red line. If he shuts the truck off and restarts it it usually goes down and will stay down, but not everytime.

He's replaced the thermostat and the water pump but is still running into this problem.

Any suggestions?

[J*B]

Possibly the gauge or the sending unit is defective?
Maybe a rad flush?

[MaO3]

Ok, the rad flush is something we hadn't considered. He thought it was the waterpump, but replaced that and its still doing it.

When I drove it and it did it, I stopped at the Post and opened the hood, the engine didn't seem like it was overly hot. Perhaps its a guage issue?

[Timbit]

flush the rad and the block, and maybe he has a vapour lock.....once you fill it back you leave it run till the thermostat opens up hot, and allows the coolant to run through to the rad and cicrulate the passages. sometimes it will get a bubble in the heater core, or somwhere that is a high spot. Jack up the front end and let it run for a looooooong time...you will sporadically see bubbles coming up through the rad and it should go down..just keep topping it up while doing this, and it should bring down the temp gauge and once the the bubbles stop coming out, you should be ok.......keep a thing of coolant in the truck for a week or so, and check the resevior to make sure it stays topped up where it is supposed to. Should be fine after that /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

[Lance]

Read this It helped this guy (http://www.ford-trucks.com/forums/639639-88-f150-running-hot.html)

If this does not work does you truck have a fan cluch like on Fords?



A bad fan clutch will certainly cause the engine to run hotter in traffic. If you hold a stationary high idle, you should audibly hear the fan engage when the engine temperature gets hot. If it doesn't (it sounds like it is not engaging), you won't hear the fan engage and thus the clutch is not working properly.

Check the link out first before worrying about a clutch fan though.

[MaO3]

Thanks guys, I'll make sure he reads this thread.

He's really had crappy luck when it comes to this truck. He's replaced the engine and transmission and both were good before. So I'm hoping its something minor for him.

[J*B]

Hard to say for sure, he'll just have to eliminate things as he's started to do already, the heat gauge sender unit is more likely suspect than the gauge itself though if it happens to be that causing the intermittent high heat readings.
Make sure you let us know what it ends up being, as we are as curious as you! /ubbthreads/images/%%GRAEMLIN_URL%%/smile.gif

[MaO3]

Where might he find the heat guage sender unit?

[J*B]

Likely threaded into the intake manifold possibly somewhere near the thermostat housing, it's been a while since I've looked for one!

[MaO3]

OK, I'll make sure he looks at that too. Like I said its a rebuilt engine that came out of another truck so he's had it out of one and put it into his.
Hopefully its something minor and this will fix it.

[Lance]

With no antifreeze smell or leaks ,it sounds like it is minor for sure.

Never thought about the sending unit,but thats a good point.

[daynzy]

There's a product you can add to your coolant to help keep down the temp on the older bigger engines.. can try that too.


One kind is Redline Water Wetter Super Coolant

[MaO3]

Cool Padman Thanks alot

[Soundbear]

Nobody mentioned the physical condition of the rad. Maybe the front is rotted out, down where it's hard to see??

I wish I had your problem. I've got a 350 Chevy I can't get to warm up!!

[MaO3]

The rad was out when he changed the engine, it was fine. He had a spare so he checked it over carefully before reinstalling it.

[Giggle Squirt]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Padman</div><div class="ubbcode-body">There's a product you can add to your coolant to help keep down the temp on the older bigger engines.. can try that too.


One kind is Redline Water Wetter Super Coolant</div></div>


See TIMBIT&gt;&gt;&gt; WATTER WETTER DOES EXIST!!!! i am not crazy!!! It is cool purple stuff we use in the race car!!!!

[daynzy]

lol, the stuff we have is bright pink not purple

[Soundbear]

First of all, check this about "water wetter":

http://www.turbomagazine.com/features/0703_turp_cooling_system_additives/test_results.html

I actually heard of this years ago, Firefighters use it to increase water throw distance by up to 100 percent.

OK, I've been thinking. Rad is good?? Hoses new?? Maybe one is collapsed inside, particularly the bottom one.
How clean is the engine? If it has a block heater, why don't you see if you can get it out to check for sludge in the water jacket.

I found years ago that a hot (195) thermostat actually ran cooler than a 160 degree. Seems to slow down the water going through the rad so it has time to cool off.

BTW, re engine temp. At operating tempersture, the upper hose should be JUST too hot to hold beyond a few seconds.

Please keep us posted.

[Soundbear]

One more thing. How about a stuck closed heat riser valve?? That thing directs exhaust throught the INTAKE, under the carb, to open the choke quicker and warm the engine.

[Soundbear]

Yet one more, though it's too late for you guys. I like to change all the core plugs (erroneously called frost plugs) on every engine change.

Cheap insurance, clean out the water jackets AND new plugs.

[fenderbass]

temp sender unit is in the cyl head(left) just above the
exaust manifold. at clys#1 and #3

[MaO3]

Well an update for you all. He took his truck in to White Pines and worked with the auto teacher on it today.

He's ordered a temp sender unit, that should fix the problem, they checked the fluid temp and it was staying at about 86 when the guage was reading 110.

[J*B]

I suspected that little bugger! lol

[Soundbear]

AHA!!!!

[MaO3]

Thanks for all your help guys, it gave him starting point.

[corn316]

one issue could be that the red antyfreeze was desinged for the newer cars for GM but ur rad cold also be pluged from inside were u dont see it if doing a flush dont change this try another thermostat some are known to be defective if not a new rad would be in order