97 Z3 Engine Cooling Issues

[matt_1997_Z3]

1997 Z3 Roadster - 1.9 - 88,000 miles

Overheated after long drive when arriving in driveway - Lost fluid, refilled when cool. There is probably a leak somewhere, searching that out.

1. Coolant was blowing out through the expansion tank cap, not a huge amount. Possible cap not holding pressure?
2. Found remnants of mouse nest in Intake Duct, probably didn't help the situation.
3. Checked front Aux fan, turns on with A/C switch. Relay slot for high speed fan is empty.
4. Have spare radiator switch but can't seem to find if that only triggers the A/C or the Clutch fan.
5. Clutch Fan spins at engine speeds but doesn't appear to ramp up when temp gauge gets above 3/4 when idling.
6. Not sure how to check clutch fan, was thinking there might be a relay but nothing in any of the fuse box diagrams. Not sure if the elusive #48 is it. Seems to be A/C related and not engine cooling.

Perhaps water pump as well? Looking for ideas.

 

[andyglym]

Probably a good time for a full cooling system overhaul if you have no history. Water pump, thermostat, serpentine belt, pullys & tensioners. Could well be a burst hose? Point to note on these is to bleed and bleed again when filling with coolant, have the front raised if you can as it help with air locks.

 

[Althulas]

As suggested time for a overhaul, could have been a burst pipe, water pump on its last legs, thermostat stuck closed and that nest adding to the mix. It’s not to expensive for a Myle water pump with metal impeller but with new belts, pulleys and tensioner does add up but at least your future proofed.

 

[matt_1997_Z3]

Belts replaced at 65K
Thermostat replaced at 66K
Tensioner and idler pully replaced at 77K
Current mileage 88K

I am wondering if the viscous fan could have issues. I can't find any reference to the actual clutch failing but I suppose it could.

I am also going to check the compression coming from the head gasket to make sure the system gets pressurized quickly after start up. I seriously hope that isn't the issue.

 

[Stevo7682]

Your problem could lie with the cap .
I changed the radiator on my m43 engine zed had all sorts of problems with the cap till I changed it.
If it is that doesn't leak till hot ( but at same time the system doesn't pressurise as it heats up hoses stay soft).
The secondary problem you may now have is as it has boiled over system may now be air locked further adding to your over heating issues.
If your engine is an m43 single cam thermal switch for electric fan is left hand upper side of radiator when viewing from front.
If you have an m44 twin cam engine the fan is a viscous unit the fan will spin with engine running ( but not be locked) when the temp increases the fan will lock and turn with engine speed.
Stephen.

 

[andyglym]

Belts replaced at 65K
Thermostat replaced at 66K
Tensioner and idler pully replaced at 77K
Current mileage 88K

I am wondering if the viscous fan could have issues. I can't find any reference to the actual clutch failing but I suppose it could.

I am also going to check the compression coming from the head gasket to make sure the system gets pressurized quickly after start up. I seriously hope that isn't the issue.

If your viscous fan has lateral movement it needs changing. Should be nice and tight with no lateral movement.

 

[Ianmc]

My Apr 1997 M44 does not have a viscos fan from factory.

 

[matt_1997_Z3]

The secondary problem you may now have is as it has boiled over system may now be air locked further adding to your over heating issues.

I was wondering about if I had an airlock as well. The bleeder screw head has been shredded so I can't even turn it. I need to dig into making sure I don't have an airlock in there somewhere.

There is a thermal switch on the left side of the radiator. I have a replacement but haven't swapped them out.

 

[IainP]

There’s also a plastic fitting at the rear of the head, it can crack and leak. You have to be careful removing it, if it is in poor condition it can break up, leaving part of it on the head. If that happens, getting the rim out is extremely difficult, needs a mirror or your smartphone to see what you’re doing.

iain

 

[matt_1997_Z3]

My Apr 1997 M44 does not have a viscos fan from factory.

I believe mine is an M44, but it does have the dual fans. The engine clutch appears to be a viscous fan. I don't think there was an alternative engine fan but I could be wrong.

 

[t-tony]

The M44 has a 16V engine the M43 has the 8V engine. Easy to tell apart.

Tony.

 

[matt_1997_Z3]

The M44 has a 16V engine the M43 has the 8V engine. Easy to tell apart.

Tony.

mine is either a 36 or 44

 

[t-tony]

A picture of the motor is the easy way to tell Matt.

Tony.

 

[Ianmc]

There’s also a plastic fitting at the rear of the head, it can crack and leak.

Had mine replaced recently as it was leaking; quite common apparently, as it gets well hot with little airflow.

 

[matt_1997_Z3]

A picture of the motor is the easy way to tell Matt.

Tony.

 

[Ianmc]

M44

 

[Daspete]

I hate to be the bearer of bad news but erupting coolant is often a head gasket or cracked head. My Zed was doing it and the head was cracked

Start your engine up from cold with the cap off and look for exhaust gas coming from the expansion tank. Do a compression test too.

What's the temp gauge doing?

I hope it's not of of these nasties but I've had this with a few cars and it's often tended to be the gasket.

 

[jonco]

"Start your engine up from cold with the cap off and look for exhaust gas coming from the expansion tank. Do a compression test too."

You can also buy a gas bubbler test kit, reasonably cheaply on eBay, which will detect even very slight leakage. Easy enough to do or your local Independent can probably do a one-off test for a similar price.

 

[OzMark]

1997 Z3 Roadster - 1.9 - 88,000 miles

Overheated after long drive when arriving in driveway - Lost fluid, refilled when cool. There is probably a leak somewhere, searching that out.

1. Coolant was blowing out through the expansion tank cap, not a huge amount. Possible cap not holding pressure?
2. Found remnants of mouse nest in Intake Duct, probably didn't help the situation.
3. Checked front Aux fan, turns on with A/C switch. Relay slot for high speed fan is empty.
4. Have spare radiator switch but can't seem to find if that only triggers the A/C or the Clutch fan.
5. Clutch Fan spins at engine speeds but doesn't appear to ramp up when temp gauge gets above 3/4 when idling.
6. Not sure how to check clutch fan, was thinking there might be a relay but nothing in any of the fuse box diagrams. Not sure if the elusive #48 is it. Seems to be A/C related and not engine cooling.

Perhaps water pump as well? Looking for ideas.

View attachment 189135

Just been through the same thing with 1.9 97 Z3. Plastic water fittings on the back of the motor. As the connections to the rubber pipes cracked. Did a full replacement of all the plastic fittings and hoses. Amazing how brittle the plastics were.

 

[Daspete]

I hate to be the bearer of bad news but erupting coolant is often a head gasket or cracked head. My Zed was doing it and the head was cracked

Start your engine up from cold with the cap off and look for exhaust gas coming from the expansion tank. Do a compression test too.

What's the temp gauge doing?

I hope it's not of of these nasties but I've had this with a few cars and it's often tended to be the gasket.

Meant to say mine was erupting out the tank cap too.