My M30 swap, few Q's

[chu346]

It has a yellow bit on the cap. I think that means it had the recall done.

[chu346]

Had a look at the car today. Linked pin 30 and 87, the fan runs, but not when the relay is in and engine upto 3/4. But the when the temp does get to 3/4's it blows out the cap. I put a new cap on it aswell. What's going on?

[Rav335uk]

Faulty relay?

[chu346]

Used the relay for the horn, which works fine.

Need to test the switch.

[chu346]

Just been out and tested the wiring to the switch. Used a piece of wire to joint the contacts and the fan came on. The plug that goes into the switch has three pins, and I am only using a single speed fan so only using two of the pins. I was previously advised to use pin 1 and one of the others as they would be for the different temperature (80/88 ). But just now wired pins two and three and the fan came on, which leads to the next problem.

The fan cools the radiator fine once it's on, but sometimes it doesn't come on then the car overheats and we get the coolant blowing through the coolant pressure cap again. Could I have air in the system or is the head/headgasket knackered?

[Rav335uk]

If it's cooling the engine and it runs on normal temp, then I would think the h/g is fine.
You have to remember, this thing is a big engine in the small e30 bay.
I would look at the relay again and make sure that its working.
Pull off the orange cover, plug in the relay and run the car.
Then operate the relay and see if it's doing it's job.
I've done this in the past when I thought the relay was dodgy.

[chu346]

The fan cools the radiator fine once it's on, but sometimes it doesn't come on then the car overheats and we get the coolant blowing through the coolant pressure cap again. Could I have air in the system or is the head/headgasket knackered?

As I said, the fan is not coming on consistantly. The relay is fine. I think it is to do with air circulating around the temperature switch causing it not to turn the fan on. What I need to know is if this is trapped air in the system or headgasket problem or something else?

[Rav335uk]

Did you bleed the system via the thermo housing bleed screw?

[chu346]

Yep

[Rav335uk]

Try holding the expansion tank higher than the engine, and open the bleed screw, you may still have air in the thermo housing.

[chu346]

Done that aswell, but it still blew coolant out the cap.

[Rav335uk]

Then if it's done that, is the thermostat the correct one??
I have an 80'C one fitted.

[chu346]

The engine was is out of a working car so unless the thermostat has gone wrong it should work fine. The radiator heats up fine. I think it might just be air in the system. I'm going to try and bleed it again now.

[chu346]

Looks like the fan isn't turning on because of a loose connection on the fan relay

[Rav335uk]

Sorted then