Overheated yesterday

[Nygdup]

Noticed yesterday driving home that my 325i was running hot when the car stopped. And sure enough, it finally overheated in that last mile before I made it to the house in stop and go traffic.

Car only runs hot when not moving, all hoses felt hot to the touch. Heat works. Sounds like a fan clutch, right?

What really bugged me was when the car overheated it started blowing out steam. The steam seemed to be coming from somewhere underneath the intake manifold.... I'm new to the m20's, is there a coolant hose that runs to the bottom of the block somewhere underneath the manifold?

[RobertK]

Heater hose runs from the thermostat to the firewall. There is also the small hose that heats the throttle body on the intake.

Fix the busted hose and go from there.

If the fan clutch is going bad the best way to tell is to take a newspaper, wrap it up, and touch it the fan while it's running.. If it stops without tearing up any of the paper it's time to replace the fan clutch.

[Nygdup]

There is also the small hose that heats the throttle body on the intake.

This small hose, does it run vertically from the block up into the manifold? Almost looked like it had a spring wrapped the hose at the base where it ran into the block.

[Nygdup]

Number 11... What is that pipe for exactly?

[chasiubao]

may be thermostat as well

try the fan clutch test as noted above...if it checks out the other thing to check out is the thermostat speaking from experience i turned on the heat one winter and thats how the thermostat got stuck and caused white smoke to come out of my car. thought it was toast but nope just stuck thermostat-replaced and good to go.

also depends on how long the engine was "hot" for could cause some head warping and you can get some weeping from the head gasket-not a sign of death but it would need to come off resurfaced and a new head gasket put on top to make it happy again otherwise you'll be good.

[MikeE30325i]

Part number 11 links the block i guess to the underside of the intake manifold. i am not sure what it does exactly.

it might be the pipe that lets coolant to the throttle body. (this is a total guess though)

[backtrail69]

Make sure that you do this test with the engine being hot, the fan clutch is designed to slip when its cold...just so you know... That pipe is the vent for the crank case vapors to go up into the head and then throught he valve cover.

[Nygdup]

At the base of the pipe is where I saw a small pool of coolant. Whether it was coming from there or just ended up there I am not sure about.

[backtrail69]

It was probably leaking from a hose near there...or you blew your HG and its leaking from there..

[Nygdup]

Fan clutch is definitely bad. I see BavAuto sells a special wrench for the fan clutch, is that really necessary? As a do-it-yourselfer, what am I up against if I tackle this myself? I assume removing the radiator, which I can do. Do I have to fool with the timing belt at all?

[Mike325]

I know you do not need to touch the timing belt. According to the Bently, all you need to do is remove the fan. The clutch is part of the fan. You could replace the fan and clutch together, or just the clutch by itself.

The nut that holds the fan to the water pump is a 32mm. You need to turn it to the right (as if you were trying to tighten something) because it is reverse threaded. This may be a good time to go to an electric fan if you wish to do so. May free up some exta HP:p

[Nygdup]

Replace the fan clutch and the thermostat while I was in there. Problem solved, thanks guys!

[PeaveyBassist]

Btw... that pipe with the spring on it is an oil return tube. It goes back down into the oil pan from the head but travels through the intake manifold first.

Will

[Nygdup]

Well, seems like it actually may be the head gasket. Car ran great yesterday. But drove it to lunch this afternoon, temp started to rise and when I got home and checked the oil it sure looked watery.

[backtrail69]

If all thats wrong is the HG then its only like 60 bucks for a HG set(at least for the 2 liter m10s). I would also replace the head bolts. Pull the head off and check it for warping and cracks. My experience with M10s... the heads like to crack. I went through 3 heads trying to find a non cracked one. I eventually just welded my head, so I could have a running car. I could do a HG in a afternoon easy.