M20: 87' 325is overheating...

[KHTRNAK]

Recently picked up this e30 a few months ago as a weekend car. Was told all of the following was done within the last few years (exact list I got from the owner):

-Odometer: 266k on cluster (4k after body work and paint)
- Full engine rebuild - only oem parts are block, head and crank. everything else was replaced and installed by a bmw enthusiast mechanic. machine shopped and better than factory specs. this engine was built to run another 250k miles. injectors clean, new plugs, wires, rotor, cap, pistons, rings, valves, cams, powder coated valve cover
- has bavauto chip installed
- Bilstein shocks, street sport - lowered - 5 years old - approx 15k on them
- new lower control arms with upgraded bushings (bavauto.com)
- caster camber kit in front (bavauto.com)
- fuel filter just replaced
- upgrade rotors and pads - ebc street sport, cross drilled and slotted rotors
- custom exhaust out rt side
- front seats redone in bmw sport red, interior trim is oem bmw sport red
- M steering wheel, shift knob
- full body and paint, back to orig black, some trim updated and painted
- yellow fogs, yellow high beams
- h4 conversion on headlights to interchangable bulbs
- new clutch with motor


It began overheating about a month ago:

The car would sometimes reach past the halfway mark on the temp guage. I replaced the temp sensor in the throttle body with a Bosche one. I also replaced the SI board on the cluster with one from a member here who rebuilds them. Put it back together and installed.

I realized the original owner had installed a rocker switch. I was told by the last owner that it was for turning the radiator fan on "on hot days."

I removed the switch and it had three connectors attached to it. They are now not plugged in. The car ran fine for a while I took it on random 5-10 mile trips in nice 60-70 degree weather. The other night it began to run hot, the gauge was shaky and would reach much past the halfway mark. I never let it get to the red but it was difficult getting it home (stopped 2-3 times) and this was on the highway driving 60mph with the heat on in like 50 degree weather. It would kind of stall but still drive until I stopped and let it cool for 5-10 minutes. Then it would be fine for 5 minutes until the gauge reached past half and start to stall a bit and I would stop and let it cool again.

Last week I started the car again after about a month of it sitting. The weather has gotten a lot cooler and I was wondering if maybe it was just too hot that night and it overheated.

I took it for a spin in 50 degree weather and it overheated within less than 10 minutes. I am not sure how or why. I had to pull over twice to get it home (only a distance of about 2-3 miles in my neighborhood, not fast city or highway driving).

After it had cooled a little once, I opened the cap on the coolant and it was about half full but not boiling or pouring out as you would expect, no?

The only thing I can think of is that before it started really overheating I replaced the coolant temp. sensor with a bosch one front Blunttech. Could that have started my issues? I hadn't really driven it too much after the replacement; this is a weekend car and I have antique tags on it so it doesn't get driven daily...Although if it were more reliable I'd like to drive it more.

I really hope it is a sticky thermostat or something along those lines....


Help?

[jlevie]

Since the engine will run hot in cold weather while at speed, the probable causes will be a bad thermostat or something restricting coolant flow. I'd start by replacing the thermostat. If that doesn't help I'd replace the radiator. I'd want to have a look at the pump to make sure the impeller is okay and I'd probably just replace it.

[KHTRNAK]

Thanks for your response!

It seems my mechanic agrees.

Took it to him today. He's not a bimmer mechanic but he works on all types of cars and has his own shop (1 man operation). Anyways so I started the car this morning after it not being driven for about two weeks. It started up and I drove it to his shop where I let it idle for about 20 minutes. It warmed up to about halfway and stayed there.

It was about 40 degrees outside and the heat was off. It just wouldn't over heat while idling there. Mechanic said it looked like the thermostat was probably replaced cause of newish marks on the bolts/housing and said probably need todo the timing belt/water pump for about 6-700 with dealer parts. So I left.

Then as I was driving home the needle steadily went up and the car started running hot. Not all the way to red but much past half. This was less than 4 miles of driving to my house from the shop. I feel like while idling it may not overheat but while running it will. Theories?


It is my impression that the car mostly sat for the last couple years been driven a few times a month. Could that cause wear to the water pump causing it to be weaker/not pump as well or as powerfully as usual? (which would be more obvious under accelerating or driving conditions than while idling)

[E30NJ]

if you do a timing belt you might as well do a water pump as well. I made the mistake of not listening to my mechanic and almost completely screwed up my engine. see if the water pump was replaced or like jlevie said, see if the thermostat was replaced. just my advice

[jlevie]

The engine not running hot at idle but overheating when being driven tends to support the theory of something restricting coolant flow. The amount of heat produced by the engine at idle is much less than when the engine under load while driving.

[KHTRNAK]

Leak down test confirms a blown head gasket.

What else should I change and what brand of parts do you guys recommend? I want to replace any wear items that will be coming off the car anyway.

[essi1553]

hell.

So:
Coolant Lines
Vacuum Lines
Timing Belt
Waterpump
Tensioner (Make sure it has z-127 stamped on it)
Spark Plugs (OEM imo)
Dist Cap + rotor
every gasket (go OEM or goetze (sp), don't victor reniz)
Injectors

Might be more...

[KHTRNAK]

Hmm..

Wel I am budgeting about $300 towards parts for this, so the headgasket kit and waterpump/tb should come in at around $150. Where do you think would be the best place to put the rest of my money (in terms of replacing parts associated with this job)

Any brand you guys recommend? I've seen mixed reviews about the Reinz kit..

[jlevie]

The head is going to have to go to a machine shop to be checked for cracks and be surfaced. And you will need a thread chasing tap for the head bolt threads in the block and compressed air to blow them out. You will also need a new timing belt.

Down tube gaskets, copper plated nuts for the exhaust manifold and down tubes, or head bolts don't come in a gasket kit. You will need those also.

Some folks have problems with the VR gaskets, but they have worked for me. Arguably, the best gaskets are the BMW OE parts.

[essi1553]

The head is going to have to go to a machine shop to be checked for cracks and be surfaced. And you will need a thread chasing tap for the head bolt threads in the block and compressed air to blow them out. You will also need a new timing belt.

Down tube gaskets, copper plated nuts for the exhaust manifold and down tubes, or head bolts don't come in a gasket kit. You will need those also.

Some folks have problems with the VR gaskets, but they have worked for me. Arguably, the best gaskets are the BMW OE parts.

A thread chasing tap? Is that to remove any excess oil that has accumulated in there?

Must have:
Timing Belt
Waterpump
Tensioner (Make sure it has z-127 stamped on it)
every gasket (go OEM or goetze (sp), don't victor reniz)

Probably best improvement:
Injectors


You really need to see what you're working with, im sure you'll find other things you want to spruce up while you're in there. I myself am doing this job again, shortly.

I picked up (so far):
Coolant lines clamps
Injectors

I've replaced just about everything, with the exception of spark plug wires, over time. Since you probably only plan on doing this job once, focus on the things that are tougher to change. If you need a clutch, having the head off will help with some of the more disgusting nuts at the top of the trans. Basically what im trying to say, when you remove thing, look at what needs to be replaced, but i'd bet your injectors have never been serviced/replaced/upgraded.

[KHTRNAK]

Thanks guys.

We got the head removed today. Couldn't find any "obvious" failure in the head gasket. Going to have the head machined tomorrow since his shop can do that for free. Then I'm going to look for a shop that has capability to check it for leaks. It wasn't that hard to remove but he commented on how easily the head bolts opened. Still not sure if it was the head gasket that failed because like I said we couldn't find an obvious failure. Hopefully the head isn't cracked otherwise I may just buy an engine and put it on a stand for rebuild and make this a more long term project.

Side note; surprisingly all the hoses and whatnot looked new or in really good shape at the very least. Maybe they were changed previously.


Thanks guys. I'm going to call my local dealer and see if I can get everything for a discount. They price match occasionally or so I was told.


So far I'm going with:
head gasket kit (assuming they have a grouped part number list)
Head bolts
Timing belt
Timing belt tensioner
Water pump
Thermostat

[KHTRNAK]

Help ?

[KHTRNAK]

Placed this order with Pelican Parts;

head gasket kit (elring)
Head bolts (Reinz)
Timing belt (conti)
Timing belt tensioner
Water pump (Graff)
Thermostat (wahler, 80deg)
Ps/Alt/Ac belt (conti)

front engine cover gasket
thermostat housing gasket
guide pin and spring for TB tensioner

Total came to around 230 bucks.


Let me know if you guys think I'm forgetting something. Head is still being decked. Found a shop that will examine it for cracks; also found a spare head that has a bad exhaust valve on CL. Might have Frankenstein and create one good head out of the two if mine is cracked.

Also, the PO wired the stock fan to a switch, I need to figure out switch it back to stock...or should I go with an electric fan? This is going to remain a stock M20 used occasionally for pleasure driving...not a track car or anything I just want to be able to drive it on hot summer days without it overheating.

[KHTRNAK]

Replaced the

head gasket (elring kit)
Victor reinz head bolts
Timing belt & tensioner, pin and spring as well
Thermostat
All other belts (3)
Bosch Spark plugs
Injectors (mepeh's refreshed m50's)
Oil and filter
Bmw coolant

Did first start up yesterday and it reached just past the half mark with the heat on full blast. Going to try to bleed it again tonight and actually take it for a spin.

[jlevie]

On crucial thing that is missing from you list of parts is a new radiator.

Bleed the system by:

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500rpm for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.