Hello,

I have read many of the related topics on this forum trying to find a possible cause of my overheating E250. The van is a 1992 with a 351W. It is an "Okanagan" camper van (related to the Airstream B190). I've owned the van for ~6 months and these months have been cooler so this likely masked the cooling problem. Or it could be that the cooling problem recently started.

Yesterday on a warmer drive home from family camping I noticed the dash temp gauge up around the "A" in "NORMAL". This struck me as odd becasue I was used to seeing the needle straight up and between "R" and "M". At points during the trip the needle made it to "L". I was driving carefully (not a heavy foot) and ambient temps were 80F. I know these guages can not be counted on to provide accurate temp values so I bought an infared heat thermometer and ran some tests this evening. I did determine that the dash gauge is reading reasonable numbers.

I started the van and let it idle for ~20 minutes. Dash gauge settled right between "R" and "M". While it was warming up I was measuring the temp at the top/inlet rad hose and the lower/outlet rad hose (thermostat housing hard to reach to get a good reading). With the guage between "R" and "M" the inlet measured 197 and the outlet measured 172. Also, I am confident that I have either a 192 or 195 thermostat in this thing because the rad inlet was measuing ~90 until it suddenly jumped to ~195.

Now, when I get in and drive this van the needle slowly drifts up and down a lot depending on the driving. For example, if I am crusing with a light foot then needle sits around "M". If I am going up a decent hill for ~1min the needle will creep up a letter to "A" (and sometimes beyond). It seems to get hotter if the E40D shifts down to 3rd and RPMs go higher. I kept driving up and down the same hill and discovered that whether the A/C was on or not made no difference. I did notice that temps went higher with O/D off (maybe because of higher RPMs?). I stopped and checked temps at different dash gauge points and discovered the following mapping:
Top side of "M" is 208 at inlet and 198 at outlet. (delta = 10)
Lower side of "A" is 212 at inlet and 203 at outlet. (delta = 9)
Middle of "A" is 218 inlet and 209 outlet. (delta = 9)

What I found was that it was common to go from 195 before the climb (between "R" and "M") to 210 after the climb (top of "M"). Once I climb the hill and turn around I can get the temps to drop back down to 195 if I coast gently down the hill at a decent speed (between 50 and 60 mph).

If I climb the hill to get 210 then pull over and let van idle it takes about ~10min to drop the temps back down to 195.

I don't have many long/large hills around me and I wanted to see how high the temps would go if I could continue climbing. It seemed that higher RPMs increased the temp faster so I decided to replicate this with the following test. It was my final test because I scared myself too much to continue testing afterwards. I put the van in 2nd gear and drove a gentle hilly country road at 40mph. I did this for about 10 minutes and watched the temps go from 195 (between "R" and "M") up to middle of "L"! I stopped the van and got out to measure these temps and as I was about to measure temps I heard the overflow jug start to boil. Just as I heard this I saw the reading on my thermometer and it was reading 265F at the inlet. Holy frick, so I jump back in the van and see the gauge is now well into the "HOT" zone. I shut the van off immediately and the boiling stopped within 30 seconds. I kept the ignition on so I could read the dash gauge and when it dropped back below HOT after ~2 minutes I start the van again to get the fan moving. I felt like a dufus to allowing the temps to get so high but I swear I stopped the van when gauge read in the middle of "L" (and "L" is still in the "NORMAL" zone). Something happened when I stopped the van and jumped out to check temps. Something caused the temps to reach the point of no return and skyrocket. When I started the engine again the temps dropped down to ~200. Well, I can definitely say this test proved that my cooling system is inadequate in some way.

My drive home was very gentle through town with lots of stops and starts and a few gentle hills. Temps climbed up to ~225 just doing this slow cruise through town. So it seems like it's getting worse.

When I got home I asked my 12yo son to jump in the driver seat and rev the engine and I checked that the lower hose was not collapsing with higher RPMs. It is not.

So, I am looking for next steps please. I REALLY appreciate any recommendations. I am about to fire the parts cannon at this thing and just install a new rad/pump/thermostat/hoses/fan clutch.

-Curtis

 

It sounds like your radiator is plugged up, like mine was
Mine didn't seem plugged up during a flush and thermostat change
It was a troublesome diagnosis for me, as I was in denial about the radiators condition
Someone had put stop leak in it and it plugged up some of the bottom fins
I'd replace the thermostat first, and if still overheats, replace the radiator

 

Thanks! The following thread is another case where very similar symptoms were caused by clogged rad:https://www.ford-trucks.com/forums/1...placement.html
I jumped the gun and ordered a new rad this morning. I will get a thermostat too and test before installing. Plan will be to install new thermostat then test. Then install new rad and test.

I also forgot to mention that the coolant in this van looks brand new. Bright green colour. This hints to me that somebody might have flushed it recently…which could lead to a clogged rad.

Also the rad cap looks new and is 16psi.

 

Sweet
Let us know
I'd maybe reuse the coolant
I could break out my coolant tester I never use anymore and see if the coolant is any good
I'd probably just reuse it without testing it