E36DJ

Yeah so I'm a little po'd, so much for German engineering

Actually jk, no car is maintenance proof, first issue on a car with 93k miles is damn good and it's either a thermostat or a water pump (both of which are regular maintenance items anyways.)

I wish I knew if it was the damn water pump or the thermostat! I'm thinking thermostat because the car has had issues either heating up with NO hot air, or simply overheating.. in the past few weeks it went a little past the middle mark on the temp gauge, then went back down (very unusual) then the other day it jumped to red. Sounds like a sticky (in the closed position) thermostat but we'll see.

As I always try to do, I'm upgrading stuff in the process.
Aluminum thermostat housing (vs. plastic OEM) new 80 degree thermostat (vs. OEM 90 degree, I'll get to this later.) Hmm, 80/88 degree aux fan temp switch, all the seals/gaskets, new belts, and a fuel filter.

I'm doing a fan delete on the thing, which should free up a few HP (who knows?) The thermostat opens 10 degrees sooner, the aux fan turns on 10 degrees sooner as well (I'm eventually hooking up a SPAL electric fan to a relay that connects to the aux fan switch which activates at 80 degrees.) I'll have a manual switch for the SPAL in the center console as well.

The belts/fuel filter are just nasty.. I feel bad.

Basically if it's not the old thermostat (and I don't fry the NEW thermostat by figuring this out) it's the water pump, which is $81 or something from an OE mail order source. The fan will be out and should only take a second if that's the case.

Either way, the aluminum t-stat housing, t-stat, seals/gaskets, redline water wetter, 2 belts, fuel filter, and 80/88 degree fan switch was only $149 shipped.

Not bad for a bimmer huh? I always get all this shit about maintenance costing an arm and a leg.

I really only "needed" a new thermostat which was $18.70, but you don't want to take risks with the cooling system.

edit: my point is.. if there's a way to figure out if it's the thermostat or the pump.. let me know.

So far someone has told me to pinch the upper radiator hose and see if water is flowing, but that's not going to help me any if the t-stat isn't opening allowing water to flow.

sk8rmike

if the motor heats up but the vents wont blow hot air check your heater core for a blockage. i wouldnt be surprised if that was the cause of your problems.

crxnfx

if your heater core is infact blocked a simple flush and fill should free that up. To check your thermostat your supposed to heat water up, using a thermometer to gauge your temp, and you should actually see it open. The plunger will pop out. Then you take it out and watch it cool, and the plunger should go back in. As for a water pump, shit I only replaced it when the seal broke down.

E36DJ

That requires me taking out the main clutch fan, thermostat housing (1 time seal.. I'd need a new seal) going home, testing the thing out.. etc.

The part is a main maintenance thing so it's going to die anyways.. plus the odds are that it's messed up, so I'll just take the car apart once and fix it.

As far as the heater core goes, good point but I thought about it (they don't usually get blocked, but they can leak) and the system is not a single-loop, then you turn on the heat a second loop in the coolant system opens up (why you have to bleed the coolant system with the heat turned on.) When the heat is off the loop closes.

crxnfx

if your thermostat, which leads to one of the sides of your loop is fucked, then that side of the loop won't open, and then their won't be any "hot" fluid in your heater core. I know that when my 190E had some cooling problems and wouldn't heat up in the car and the engine wouldn't cool down, it was because the thermostat was rusted shut and refused to open. Again, German engineering

E36DJ

Sweet.. no that makes me feel really good because I figured that was the problem. Well the parts are on the way!

Shit I have to drain/bleed my coolant system

HatefulMechanic

i am willing to bet money that the impeller on the water pump is broken off.


most every german engine has a plastic impeller, and they will break causing no coolant flow. it will look identical to a bad thermostat.


i have replaced only two thermostats in my entire career that were actually defective. most of the time, whenever the system is serviced, i replace it as cheap insurance.

what kind of car/engine?

E36DJ

97 M3, S52..
95 through early 96 model M3s (and '92 to early '97 3 series) had plastic impellers, mine's metal.

I'll know soon enough.. no harm in waiting a few more days if it does turn out to be a water pump, the thermostat needed to be replaced anyways.

A water pump wouldn't explain why my car was slightly overheating weeks ago many times, a sticky thermostat would though..

BSeriesTurbo

btw that wierd screw next to the filler tank/reservoir is the bleed screw..took me a while to figure that out for some reason when I was workin on my moms 328...

NastyNate

Yeah sounds about right. E36DJ...since you will have the shroud out with the fan go ahead and pull the pump while your doing the thermo and housing...Id say about 75% of the E36's we get in here have a plastic impeller h20 pump and usually the impeller is always seperated from the shaft. I can sell you a h20 pump with the metal impeller cheap if interested...Pm me if you want.

Nathan

EDIT: Sorry E36DJ, I didnt see your last post about having the metal impeller already...disreguard.