Hey fellow D2 fanatics, funnily enough I am having overheating trouble in a -20f climate.


My '01 D2 ran flawlessly all year through the summer on many trips with the AC on but for some reason randomly overheated on a 1 hour drive right after my heater stopped blowing hot air in -20f a few weeks ago.


I towed her home and replaced the thermostat, flushed/backflushed radiator and flushed/bflushed the heater core/block, flow was clean and without chunks etc. replaced coolant with a green ethylene glycol concentrate and distilled water 60/40. I bled the system thoroughly many times following instructions I found on here. truck will run for half an hour or more in the garage and temp sits right where It should, as soon as I take it around the block a couple times it overheats.
discovered that I could stop the viscous fan with my finger easily so figured the clutch was burned out. fitted a new one today and it works perfectly except the truck overheated again after a 12 mins drive, I hit 45mph after some slow driving around the block for 10 mins and the heater went cold and temp shot up.


Any suggestions greatly appreciated I am pulling my hair out, I have a job interview on Fri with the sheriffs Dept that I have to get to (if I get the job im selling the D2 and getting an 08 HSE D3)


Also I pressure checked the cooling system tonight, pumped it to 15 PSI and it shed 5 PSI in 10 mins. I noticed a slight hiss of air from the seal on a new overflow nipple I put on the radiator a month ago, could that cause the overheating??


Josh

 

What temps are you running? What brand t stat did you replace with? and are you talking about the bleeder screw on the plastic tee? or did you put a "nipple" into the top of your radiator? If its hissing it's not airtight your losing coolant for sure if its hissing. I just replaced My tstat with the OEM 180 Gray unit and swapped out rad with new one. I run about 182-186 norm driving I would say 96% of the time it never exceeds 199 - 200 (ultragauge readings)

 

thanks bmeier, I foolishly ordered a 190 stat from ebay for $28 PART # PEM100990 which I believe is a genuine part. I couldn't tell you the exact temps as I don't have an OBD2 reader currently. I don't seem to be losing any coolant from the nipple. I don't mean the the bleed screw but the overflow nipple got knocked during a steering box swap and broke off so I drilled it out and fitted an aftermarket radiator nipple that is actually a lot stronger and thicker than the little stock one. however it has its limits and the first time is overheated on an hour drive coolant was pouring from the expansion tank cap and hissing from the new nipple, it would seem that the seal can only handle a certain amount of pressure. funny thing is, it ran just fine for a week or 2 after I fitted that nipple.... what did you pay for a new radiator? the one I have seem to be in pretty good condition ( I have had truck a little over a year) when I flushed system it was clean, green and flowing well.

 

No prob, I just got mine, thanks to some helpful peeps on here for their recommendations. Rock Auto seems to be the cheapest place so far. It's where I got mine for a little over 190.00 bucks

radiator part# Nissens #64313A
The T-Stat I got from Rovers North for I think 95.00 or so, (they give you some free stickers though lol) highly recommend.

 

I'd say the next step is to buy an infrared thermometer (~$25), crank the truck, and measure the temps across the front of the radiator. If it's much cooler toward the bottom, you need a radiator.

You should also toss the truck's thermostat into boiling water for a minute or two, pull it out with tongs, and see if it opened.

 

Re: " hissing from the new nipple "

It sounds like you do not have a completely sealed cooling system and you may be introducing air back into system.

It appears your engine overheated a number of times. You mentioned you do not have an digital gauge to give you realtime temp readings. It appears you are referring to the coolant gauge to infer that the engine has overheated. This factory gauge is not linear. Once you hit a certain temp mark (I believe it is 250-deg.... someone correct me if I am wrong). The constant overheating could have possible affected your head gasket.

My suggestion since you only have a couple of days left to the main event.... is to see if you can re-seal the radiator connector where the hiss is coming from. Pressure test it again to see if there is any increase in pressure. Perhaps try and do it tomorrow or Thur morn at the latest.

If the result is negative, you could face a string of other diagnosis that is going to take your time. Confirming if the hiss is your problem by Thurs morn will allow you some time to make a contingency plan (e.g., rent a car, call a buddy to give you a ride on Fri).

It sounds like the interview is a major life milestone if you get the job. I would not stress past Thurs on the Disco. Give yourself some time to relax and prepare for the interview.

 

P/S. Is the fan belt is routed correctly?

 

J B Weld is your friend

 

thanks for all the help guys, I did in fact route the belt wrong once, ran truck for less than a min before I realized it, only seemed to temporarily affect my alternator but no lasting damage. I will double check routing again in the morning, I will invest in an infrared thermometer to check radiator as well as fit a new nipple as this one is kinda chewed up from roadside repair attempts apon initial break down (leatherman's work wonders). If all this fails to diagnose I will pull stat and test with boiling water, I am reluctant to do so as I will lose a gallon or 2 of expensive antifreeze which means another begged ride to the auto store. Could I be pumping to much pressure into the system with test kit causing 'nipple' to hiss? does anyone know what the standard operating pressure of the cooling system is? obviously the little overflow 'nipple' wont handle ridiculous pressures like 200PSI but the testing pump only goes up to around 25PSI so if I can jimmy it to handle 20 or so I should be alright, thoughts???


P.S thank for all the suggestions, ACG, I will take your advice and relax for the interview, I have one with Altoona City fire and rescue tomorrow (thur) night at 6pm as well as the sheriffs dept. on fri so I need to be in a straight frame of mind and forget about my beloved disco for a while. BTW I grew up in some pretty rough country back home in Australia and the Switch last year to Northern Wisconsin brought some suprises, if any of you ever want an area to 4x4 in while visiting Aus, I have some good mates who would be happy to show you around lend a truck and let ya shoot some kangaroos. just PM me for some names to drop as well as phones numbers. Cheers

 

Operating pressure is ~15 psi. I wouldn't pump it over 16 psi. Above 15 psi the system will depressurize itself. That's probly the hissing you're hearing.

Before you pull the thermo, just yank the bottom rad hose and push it into a bucket to drain the system. Then reuse your coolant.

I'm thinking one of three things is most likely your problem - thermostat, radiator, or you didn't fully bleed it (I know you bled it, maybe you still had air?).