Engine running hot

Tiny
CHRISTOPHER SA
  • MEMBER
  • 1993 BMW 320I
  • 2.0L
  • 6 CYL
  • 2WD
  • MANUAL
  • 118,000 MILES
After working on my car with an ignition problem for over eighteen months I got it working yesterday and after taking it out for a spin there is one worrying issue that has come up which was not there before the car got this problem. The needle in the temperature gauge goes all the way towards the red without actually going into it (it normally sits in the middle when fully warm).

After letting the car sit for twenty minutes with the engine turned off, I checked the coolant level and also tested its temperature. While the engine was still warm the coolant in the collector bottle on the left of the radiator (passenger side) was cold. Didn't feel as if it had been circulated. Yet when I was twisting the cap off I did notice the level change as the pressure was released. There is a socket/switch (temperature switch?) On that side of the radiator housing that is disconnected and has always been that way since I had it. The plug that goes into the socket is present but is just hanging there instead of being plugged in. I get the impression that it is like that because it does not work(?). How do I test that plug/socket to see if there is anything wrong with it?
Do you
have the same problem?
Yes
No
Saturday, January 12th, 2019 AT 2:48 PM

5 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,554 POSTS
Hello,

It sounds like you have a bad thermostat. here are two guides to help us see whats going on:

https://www.2carpros.com/articles/replace-thermostat

and

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Please run down these guides and report back.
Was this
answer
helpful?
Yes
No
Sunday, January 13th, 2019 AT 11:28 AM
Tiny
CHRISTOPHER SA
  • MEMBER
  • 206 POSTS
Hi Ken,

I haven't look at all the videos yet, and since everything is closed here on a Sunday I washed my car (in -5 degree weather) and turned it on and let it warm up to see if the interior heat came on (to de-frost the windshield!). When the engine got up to operating temperature, which took a while, the hot air blew cold. That tells me that the thermostat is stuck in the closed position(?) Or is it the opposite? I don't know how heat is transferred from the engine coolant to the hot air blower system for the interior of the car but that seems to be the logical thing to think.

The car had been sitting for about 19 months without being started and I have no idea what effect that would have on the thermostat. Since I have no idea if the thermostat had ever been changed since the car was purchased, this would be the logical place to start.
Was this
answer
helpful?
Yes
No
Sunday, January 13th, 2019 AT 2:03 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,554 POSTS
I didn't mention this but did you check the coolant level?
Was this
answer
helpful?
Yes
No
Monday, January 14th, 2019 AT 9:48 AM
Tiny
CHRISTOPHER SA
  • MEMBER
  • 206 POSTS
Hi Ken,

I checked the coolant level and it is good.

I got a new thermostat for the car but before I went to pick it up I had a look at the engine compartment again and did some things to the radiator and one of the wires that I disconnected.

With the wire, it is the one that is attached to the engine block by a large bolt near where the fuel rail starts. It is a grounding wire for the fuel rail. I unbolted it and gave it a thorough clean with a green scotchbrite pad. I also cleaned the part of the engine block where the wire loop/washer sits against it when bolted to it. I also cleaned the bolt washer. Then I put everything back and tightened up the bolt properly.

Then I had a look down the front of the radiator and found that there were a lot of cobwebs, dust/fluff buildup. So I took some rigid wire and swept it across the front of the radiator knocking all this stuff off.

I then took the car out for a drive. After a while, and with the temp gauge needle in the normal range, I turned on the heat inside the car and found that it was blowing warm air. Much better than before. During the course of the drive the needle would move off to the right towards the red zone but would then come back to center. The air also become much warmer. So it seems that this problem is sorted out. I did go ahead and buy the thermostat and as well as the gasket and will buy an aluminum housing for the thermostat housing and get them both changed as the original plastic housing is on the engine which means the thermostat has probably never been changed. It will be a good preventative measure. Thanks again for the help.
Was this
answer
helpful?
Yes
No
Monday, January 14th, 2019 AT 3:50 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,554 POSTS
Nice work, we are here to help, please use 2CarPros anytime.
Was this
answer
helpful?
Yes
No
Tuesday, January 15th, 2019 AT 10:51 AM

Please login or register to post a reply.

Sponsored links