car guys i need help

its my Isuzu P'UP. So far this has everyone i know stumped even my friends over at isuzupup.com. My P'UP (1986 Isuzu P'UP 2.3L spacecab 5speed) has been over heating from the day i got it. I will start by telling y'all what i have done to it so far

1. rebuilt the head
2. cut off the cat converter
3. flushed the motor countless times
4. pulled the rad and cleaned it inside and out so many times its not funny no more
5. New water pump
6. tried a gutted thermostat and a new thermostat
7. replaced the stock carb with a weber 32/36
8. removed the air pump and air inject system off the head.
9. i been removing everything i can from under the hood to get better air flow over the motor and beleave me i can tell a difference.

only time it will not over heat is if i run the heater and noway will i do that during a GA summer. If i run the AC on full it makes no diff on how fast it over heats. If i am sitting in one spot with AC on high just holding the gas 2000-2500RPM it takes longer for it to over heat then it does doing 45-55MPH. last thing i can think of is the rad is just to old to provide the cooling needed to cool the water. Thanks to any help and if i missed something just take me behind the shad and shot me

 

That got a clutch fan?

How far from the radiator does the fan sit? May need to put a spacer between the fan and the block..

 

Yes its got a clutch fan and it sits afew inches away from the rad with the stock fan shroud around it to channel the air flow.

 

Read your posting over at isuzupup.com too and have to agree with your heater core suspicions. The fact it is the right hand side passenger footwell where fluid collects, added to the heating problem and the fogging all bring back memories for me of my Kia.

Have you checked whether it is pure water or coolant? Good indicator of whether you have a cooling system leak or a rainwater leak into the cab. Sounds like you might have 2 separate issues going on there. Yes, replacing the core is a PITA job...been there done that. I too had overheating problems, ran the fan on high to keep it cool, windshield misted up, but I wasn;t lossing any water...until the fateful day it emptied the whole cooling system contents in my passenger footwell in one almighty go while blowing the radiator at the same time. Really embarrassing when you are getting tanked up with gas at the station :innoccent

 

It may sound dumb, but is the Rad Shroud in place, fan sits inside the shroud or just at the entrance and the Shroud funnels the air through the Rad, then over the engine. I have a Old Jeep J-10, which was a real knuckle buster with the exposed Fan so I extended the shroud with Fiberglas, and a side bonus the old girl would not overheat in Rush Hour Traffic. Just a thought, MeitHed's Idea sounds like a plausible too

 

I am not familiar with your Izuzu but this sounds like a circulation problem you say if you run the heater it does not overheat that suggests that the heater bypass is blocked, normally you find this on the underhood controls it is a unit with 3 pipes and a cable attached 2 of the pipes are for the heater and the other is for when the heater is off the water goes straight back to the system if this pipe is in any way restricted it could be the cause.

hope this is of some help and not just a rerun of somthing you already did


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Lev the heater core is fine the fogging and water in the cab was solved the drains for the sunroof was rusted out and caused the leaking into the cab so i just used some RTV and sealed the drain for the sun roof that was leaking and no more water in the cab and no more fogging.

BCG the fan sits almost all the way inside the Rad Shroud only a little bit is not inside it.


Bill i will have a look in the morning but one thing about these P'UP's they were built simple but will run forever


i am going to bed had a long day (putting that Weber on it) good nite y'all

 

Okay how about Rad Tubes blocked even though you have cleaned it, most retail cleaners will not free restricted tubes, need a Rad shop to clean out the stubborn stuff...............Also can you see through the Rad fins, know some Off Roaders that have clogged up there rads with good old backwoods gumbo that caused overheating

 

The rad has good water and air flow through it. This truck don't see off road to much. Now if it was a 4x4 2.2L turbo diesel version then heck yea i would be off roading it

 

Dang it N5638J can see why your stumped, there has to be something restricting water flow, couldn't be bad design as others would have it as well, collapsed hose, head gasket restricting water flow.......Hey how about faulty gauge or is it actually boiling over, Rad cap ????

 

It may be as simple as a bad radiator cap..... rolleyes but then I had a cooling prob that was actually a cracked head. It was cracked in a way that combustion gases got into the coolant (but no coolant was getting to the oil as a sign) and blew coolant out the over flow, causing it to overheat. A bad head gasket can do the same thing.

 

Its not a bad head gasket i replaced that and the intake gasket when i rebuilt the head. there was a common problem with the 2.3L 4ZD1 motors and that is the head cracking from the cat clogging and causing it to overheat at the outlet side. its not boiling over in to the over flow as a matter of fact its draining the over flow till theres nothing left in the overflow but never drains the rad. i don't think the gauge faulty it seems to be reading right. I just put a new rad cap on it and i don't see no water in the oil, no oil in the water and no air bubbles in the rad to. I know one thing just running the engine for a few mins it makes the intake so hot it would burn the skin off your hand.

 

Just another thought it's difficult without seeing the motor.

is the valve timing spot on?? if not the hot gas could escape back into the intake and unlike a petrol motor a diesel will run with bad valve timing

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Sounds like you've tried almost everything, but if it runs cooler when the heater is on, I'd guess it's a blocked or partially blocked radiator core. Radflush or whatever equivalent brand probably won't clear it if it's bad enough to cause such serious overheating. You could check it by taking the radiator out, and putting water through it to see how quickly it empties. The passages through a radiator are extremely thin and it doesn't take a lot for them to become restricted. If the vehicle has at some point in its life been run on pure water rather than a mix of water and coolant, it could get so blocked up it would make the engine overheat.
A mate of mine bought a car once with a suspected blown head gasket. It had overheated. He took the head off and it was fine, but there were a couple of burnt out valves. Luckily he damaged the plastic top tank of the radiator when he was putting it all back together. When he took the rad to a workshop for them to replace it, the core was blocked solid. It looked like it was filled with cement. No wonder it had cooked the engine. I don't know of anything that would have cleared that out, and he had to have a completely new radiator. The car ran nice and cool afterwards. If all else fails, maybe investigate that possibility. Could you borrow another radiator to try out and see it the problem goes away ?

 

Have you checked your radiator hoses to make sure they aren't partially collapsing? I ran into this on a Mustang a couple of years ago.

 

Bill its not a diesel its a gasser and the timing might be off alittle but you can't tell when its running it runs and sounds like if it was brand new

Tarquin the rad is not clogged it has as good of flow as a new rad but i think it may be just to old to cool it good enough

Novice all the hoses on it are new

I got to go its lighting and i don't want anything to happen like before

 

It runs cooler when the heater is on because the heater draws heat off the engine..

 

Just another thought on this. What type of thermostat has it got ? Some are the simple kind, which just opens and allows water to circulate. But the other type has an extra piece which blocks the bypass hole when it's fully open. If it needs this type and either doesn't have it or it's faulty, the bypass hole won't get covered and instead of water circulating round the system to the radiator, it simply goes round from the pump to the block, and the engine temp keeps rising. Some BMWs have this type, as do many of the twin cam Fiat engines and several others I can't think of.

 

its just got a simple thermostat ;

yesterday i took the heater core hoses off and there was abit of rust in the lines so i took the water hose and flushed the heater core out and cleaned the lines. and its a new newer heater core because the stock one had metal ends and this one ahs plastic ends. Theres good flow through the heater core and with the heater core lines off (also the bypass hose. I guess thats what that was) i ran the water from the water hose through the rad and it had good flow coming out the heater core lines and the bypass.

So now i am guessing because it has good flow and all that the rad is just too old and just can't provide good enough cooling needed anymore.

 

Its nice to see people still have "older" cars....I traded my '87 Tornado in for a '01 Grand am....got sick of working on it...and well it was a gas hog..... anyway if you cant find the problem take it to a garage n spend a lil $$ in the long run it prolly would of saved you money