Idle problem

I have an 84 528e. The idle speed is a little high. I noticed a vaccum hose disconnected and when I reattached the hose the idle went down. The next day It started doing it again and I inspected my hoses and there does seem to be a little play with the vaccum booster hose but nothing that would seem to cause this rise in idle speed.

Aslo my ICV is working within specifications. Anyone have an idea what the problem is?

Inspect all your rubber hoses and boots and replace any that are suspect. Rubber deteriorates over time, especially if subjected to heat and oil and gas, and it can be difficult to see the tiny cracks. You may also want to replace your rubber fuel lines as preventative maintenance. They are also prone to leaks that will cause gasoline odors and possibly a fire. Also try cleaning your ICV valve and inspect your cold start valve, which is known to be problematic.

I recently read on another post a similar problem and the solution was switching the wires on the coolant temp switch. I did this and the high idle has been fixed, but now I've noticed it has an intermitent grumble when in the warm up phase, which wasn't there before.

I think I got most of the hoses. The hose to the brake booster seems fine, but the 90 deg fitting that connects the hose to the booster is the thing that plays. It's one of those one way push fittings, which i've taken out before and the only way seems to be cutting. Is there a technique you know of that won't damage the booster?

Also, I should note I noticed this problem after doing my head gasket. All of the hoses around the intake are solid and new. Can the connector on the coolant temp sensor be put on backwards or is it a one way fit?

And the o-rings to the injectors are new too.

I dont really know about the sensor, but there could be a vacuum booster leak, maybe even internally. Someone recently posted who has put a nice rebuild kit together. Why dont you try clamping the booster hose (thereby stopping the airflow) to see if it has any effect.

There are 2 coolant temp senders. One runs the dash gauge, the other gives info the the ECU. I think the plugs are keyed to prevent crossing, but who knows what a PO may have done..

Thanks I'll try that. However I just found out today that my gasket wasn't the problem. I might have a cracked head or block. I had the head milled but didn't have it inspected for cracks. Coolant is still leaking into the oil. So what are the odds it is a cracked block and not just the head? I'm thinking since the block is cast iron I have a good chance it's just the head.

I drove it for about 15 miles without any coolant and then when I pulled over I poured in cold water which just steamed (I know dumb idea).

Originally Posted by beamer528e

Thanks I'll try that. However I just found out today that my gasket wasn't the problem. I might have a cracked head or block. I had the head milled but didn't have it inspected for cracks. Coolant is still leaking into the oil. So what are the odds it is a cracked block and not just the head? I'm thinking since the block is cast iron I have a good chance it's just the head.

I drove it for about 15 miles without any coolant and then when I pulled over I poured in cold water which just steamed (I know dumb idea).

You may want to consider swapping in another motor.

I've been looking at used engines and heard an 84 325 has the same engine as a 84 528 is this correct?

I'm pretty sure it's the same.

Originally Posted by beamer528e

I've been looking at used engines and heard an 84 325 has the same engine as a 84 528 is this correct?

If it is a 325i it is different, if 325e, then they are very close. The oil pan and a very other things are different.


Andy