Well hello there..

Got my 02 on the road, and have been battling an annoying cooling system the past couple days.

Here's the story, the truck does fine idling, or around town 25-26 MPH. As soon as you get to 35+ and constant throttle it will slowly start to overheat, no water spilling out or anything just the temp gauge reads red. I wish I had an infrared temp reader, or someway to see if the thermostat is opening but I unfortunately don't. Never have had an issue like this before. I wonder if IIDTool would connect?

All hoses get as hot as you'd expect, so thermostat seems to opening. New thermostat from LK8, 180deg, running 100% water for the time until I can figure out the issue so I don't waste expensive BMW coolant. Changed viscous fan to known good one, has good resistance. Burped all lines, can not get any more air out of the system, tried a few other ways I found on the forum and youtube as well.

This all started after a head gasket replacement.. Headgasket was leaking coolant out the back, never overheated though. Was running 180 deg Motorad thermostat, heard too many bad things about them so obviously this time LK8 got a call.

While it's running it goes like a scalded cat, a slow one but still. No water out of tail pipe.

Any input? I'm kind of stumped, tia

(EDIT)
also new water pump and radiator, replaced pressure cap to new one same thing

(EDIT 2)
Checked belt diagram, it is correct so pump isn't operating backwards..long shot but still looked

 

Jeez, so many threads like this recently

 

I've had nothing but good luck with motorad. I just put a brand new one in last night

 

 

are you reading the temp from the dash gauge or do you have a gauge you can plug in to the OBD2 port?

 

If it’s not frozen throttle bodies in the winter time (hahaha...) it’s over-heating problems in the summer time.

 

Shane: I have read many things about the Motorad units randomly failing. I use this truck for hunting/fishing trips up north, an 800 mile round trip. I did not want any issues.

Collie: The gasket was replaced before this issue, heads were within spec. I would certainly hope it wasn't another bag gasket haha!



Jastutte: I was reading the actual temp gauge. If it was close to the light coming on, I would shut it off and coast until I could restart and inch closer to home. Luckily I live in a relatively low speed area, so wasn't bad getting home. My hope is to invest in a proper DII reader, all of my stuff works on L319, L320, and L322+. When I connect it to my L318 it just goes into a bootloop. I've never really needed diagnostics tool in the many years I've owned my Discos and Classics, they've been dead reliable (Knock on an entire forest)..........



We have good news! My new black Britpart thermostat is not opening all of the way (My assumption). I reinstalled my old Motorad 180 deg stat about 5 this morning and it never left the middle on the temp gauge, even after a spirited drive this morning.

I'll have to contact lucky 8 and get a replacement.

 

Lol yea.

I wonder if people know that your coolant levels change with the weather. Guess not.

 

Does your Motorad 180 open at 180? The issue with mine was that it was a 195 degree thermostat not 180. Never failed on me.

 

That's just it. They dont fail. I bet if you put it in a pot of water it will open exactly +/- 3 degrees.

The fail in the system is air.

Why can the people that designed the system, the tech that work at the dealerships, and most of us here bleed our systems and not have an issue?

Yes it's somewhat of a poor design system, and the dexcool really sucks, but I remember motorad being the thermostat to get years ago...now what? They went belly up and make garbage? I dont think so.

BLEED it and I wish everyone would stop blaming the t-stat, over and over....bleed it again. You cant just pour the fluid in and think it's good, squeeze your hoses, feel the heat, put a thermometer in your vent, take it for a drive, park it on a hill, then add more coolant and take it for another ride.

You just have to bleed it. It's not the stat unless it's old and the two seep holes may be clogged.