1991 6.2 chevy diesel help

okay gentlemen....... my parents have recently bought a 91 suburban, with a 6.2, 3 speed automatic, 3/4 ton..... its got a diesel tank heater, fuel line/ fuel filter heater, and block heater on it...... runs good, strong running...... heres the problem....... it never warms up.... i drove it 120 miles, and the motor never warmed up enough to move the water temp gauge..... it wasnt even warm enough to defrost the windshield, the whole trip.... i got back, replaced the thermostat, water temp sender, and hooked a manual temp gauge up as well.... drove it around for 30 minutes, and still eont warm up..... what the #@#@?...... im out of ideas on this one.. any thing else to look at? oh, i blocked the radiator even, and no dice.

perhaps the temp guage is wrong and maybe the heater core is clogged up.. i dont know deisel trucks to well but i would imagine the cooling system isnt much different... i know we installed to cold ot a t-stat on my buddies eclipse and it wouldnt heat up worth crap..

well, its got a 190 thermostat, a electric and manual temperature gauges on it..... i just replaced the sender and stock gauge, and installed the manual gauge.....

Try cardboard over the grill and see if it heats up anymore. If it does, you can get a velcro winterfront made or a snap on one. Just make sure you dont completely close the grill off to the incoming air. Also, does it have a rear heater? If it's very cold, the antifreeze in the rear heat lines run down the frame and it really cools it off because it disappates into the frame.

IIRC, there are two senders for water temp.

One, for the gauge, and one for the ECU.


If the one for the ECU is bad, it could result in that.


Providing it has two, of course.

it doesnt have rear air, i tried blocking off the radiator, and it didnt do anything after 45 minutes of idling.

where would i find the sending unit for the ecu?

its a deisel truck so it only has one sensor.. should be at the back of the block by the exhuast manifold..

I think it's on the back of one of the heads.

i replaced the one on the back of the block, and no change.

is there one by your thermostat house.. thats about the only 2 places i know to look.. if it has electric fans then put a switch inline with the wires and youll just have to check the temp guage to turn it on and cool it off..

batty1214 wrote:

it doesnt have rear air, i tried blocking off the radiator, and it didnt do anything after 45 minutes of idling.

diesels dont make much heat idling. Try blocking off part of the rad. and driving it around the mile. I know my 7.3 never gets really warm in the winter.........

Is the block a 'c' code or a 'j'code? IIRC the 'j' code motors have 2 thermostats. Its possible one is stuck open.

i dunno what code the motor is....ill have to look tommorow.... where would the 2nd thermostat be?

Do you have the VIN? I could tell you from that.

i dont have it here, but can get it in the morning.

Get a power inverter and a small electric heater. Problem solved lol!

thats what my dads been doing, and its not working real well, but it does beat walking to work.

Well, ya gotta make do with what you got.

Have you checked the fan clutch? If its staying engaged in the cold weather it would be very difficult to warm the engine up.

Ok whats the water temp on your 6.2 Diesel ?

Dose your heater fan blow air ? its just cold ?

Mike

oh, its not even at 120...... and the heater blows cold, even after 3 hours of driving, it is still cold

Ok, has the thermostat been replaced lately ? . . .

if so you might want to pull it out and check it sounds to be stuck open, due to some thing caught in in it or a weak spring, i have had new's fail on me . . .

Mike

I have replaced the thermostat twice....... after I pulled the 2nd one, I started heating water, and at 190, it opened just as it should.............. so, I reinstalled it........ I have blocked off the radiator, replaced the thermostat, I havent checked the fan clutch yet, dad had it, and I didnt have time to wait.

I'm still betting its the fan clutch.