325i motor using eta ecu and pulleys - water pump issue?

[Camper Van Someren]

Hey all, my first post here. I just bought an 86 325eS racecar that has run in the 24h Lemons many times. I’m hoping to do the same. Most recently the car raced 2 years ago - since then it has sat for 2 years in Phoenix, but the owner said he drove around the block every couple weeks. First thing I wanted to do after getting the car was a coolant flush because they use water in the racecars. I was able to drain lots of rust colored water from the radiator and engine block (the coolant bolt on R side of block). Because there was some sediment I also flushed both the radiator and block with hose water, then filled with water. Next I closed the drains and started it at idle. I opened the bleed valve (front left of engine) but I never got coolant come out the valve. I let it idle 5 minutes and there was definitely movement in the expansion tank which turned rusty colored again and eventually started to steam. The radiator hoses never got hot and I confirmed shortly after that the radiator had cold, non-rusty water. Definitely seems to me that the coolant/water isn’t circulating between the block and the radiator. Bad water pump? Hose blocked by rust/sediment? Could it be a thermostat issue? Where would you start troubleshooting this issue? Appreciate any input.

[Vincenze]

I lift the front of the car with a jack and turn on the heater to the maximum position.
I disconnect the hose that goes down from the thermostat and fill it with the coolant completely.
When it's full, I connect the hose.
Then I disconnect the upper hose that goes to the radiator and fill it too.
I start the engine and periodically unscrew the bleeding screw.

[tomstin]

Generally accepted that raising the front of the car to get the bleeder as the high point works well. I like Vincenze's process. Since you are using water, and not antifreeze, I would drain everything again, and use Vincenze's method.

[Camper Van Someren]

I lift the front of the car with a jack and turn on the heater to the maximum position. I disconnect the hose that goes down from the thermostat and fill it with the coolant completely. When it's full, I connect the hose. Then I disconnect the upper hose that goes to the radiator and fill it too. I start the engine and periodically unscrew the bleeding screw.

Thanks for the input. I didn’t lift the car, and I think the heater core has been removed (because racecar). Otherwise I did what you suggested. I filled the radiator and block through disconnected hoses, then reconnected, then filled the expansion tank. I heard air escaping through the bleed screw while filling so I know at least that isn’t blocked. When I started the engine I left the bleed screw open for minutes and never got any coolant/water out. That is part of the reason I think the water pump may be bad, because if it is circulating then it should eventually come out the bleed screw correct? Edit - lifting to get the bleed screw high makes sense. Maybe it was just a big air bubble that prevented it from circulating? I’ll try it again with the front lifted. I’ll also measure to see what the temp gets to in the expansion tank, and see if the radiator coolant gets to the same temp or stays cold.

[Vincenze]

If it's been sitting in Phoenix for 2 years, It's better to change the timing belt.
Then, it'll be easy to change the water pump and old hoses.
You can use a radiator flush to clean more rust and scale.

[Camper Van Someren]

Ok, My question: when you bleed the coolant do you get air/coolant out of the bleed screw immediately upon starting the motor, or only after the coolant is up to temp and the thermostat opens? Thanks to all for the suggestions! I tried bleeding again with a flush compound, this time with the front jacked up. I hand-pumped fluid through the small top radiator hose as some have recommended, and this spilled out the expansion tank but not out the bleed screw on the thermostat (which was open). Then I idled the motor for 10-15 min, but never saw any coolant out of the bleed screw. So maybe the bleed screw is just clogged with rust. However, the temp in the expansion tank got to about 180F (on a meat thermometer) and the car’s coolant gauge also indicated about 180. All of the radiator hoses eventually got hot to touch but they never got “firm” even when revving the motor. They were always very easy to squish by hand. I think this probably means a bad water pump. Apparently the timing belt and water pump were changed 4-5 years ago, which isn’t many miles for this car. But I’m suspecting that all the rust in the coolant has caused the water pump to fail.

[tomstin]

Apparently the timing belt and water pump were changed 4-5 years ago, which isn’t many miles for this car.

Replace the timing belt! AS I recall the service interval is 3 years, and particularly after sitting, it needs to be changed. Cars do not age well sitting still, and timing belts will take a set which is very bad for them. Do not delay!

[Camper Van Someren]

Replace the timing belt! AS I recall the service interval is 3 years, and particularly after sitting, it needs to be changed. Cars do not age well sitting still, and timing belts will take a set which is very bad for them. Do not delay!

Thanks, I just ordered a timing belt kit and will do the water pump then also. I’d still like to know whether I should get air/coolant out of the bleed screw immediately upon starting the motor, or only after the coolant is up to temp and the thermostat opens. Anyone?

[Camper Van Someren]

Bump Any thoughts on how soon I should expect to see coolant out of the bleed screw when idling the engine?

[Vincenze]

Almost immediately.

You can add coolant through that hole too.

[Camper Van Someren]

Almost immediately. You can add coolant through that hole too.

Thanks, then that must be another symptom of a failed water pump. I guess you could add coolant if you completely remove the bleed screw? Even so you’d need a tiny funnel because the hole is so small...

[ForcedFirebird]

Welcome fellow e30 racer ;) 13yr veteran at an e30 specialty shop, 6yr racing e30's with NASA/Champcar here.

Having dealt with many neglected e30's over the years, stop running the car immediately, the belt is probably dry rotted, you can use a coolant pressure test kit to diagnose the cooling system statically. If you plan on racing long endurance races, might want to invest in one, they make finding a coolant leak/problem pretty instantaneous, and you don't need to be messing with a hot system to do so. I had an e30 at the shop several years ago, in for a lifter fuel pump, the belt literally broke when I went to start it and move it in the shop! Broke the head off a valve, several rockers and the valve damaged the piston so bad, engine was rendered useless aside from block/crank core.

The water pump is behind/beside the timing belt, so it's right there anyways, and typically we do them at the same time, along with the tensioner - also a good time to check/replace the cam/crank/intermediate shaft seals while there. Go ahead and pull it apart and see what's in there. More than likely you have rust blocking passages, and all your freeze plugs will be paper thin. I had a motor sitting in a crashed race car, stored inside the shop for 2yr, took it out to replace the one in the endurance car, and the night before the race checked it with the coolant pressure tester, sure enough - freeze plug burst! Had to change them in the car, in situ, all 11 of them, was there until 4am. That was NOT fun.

The fuel system will also need to be gone over. Fuels today aren't very combustible, even after a single year, and adding the 10% ethanol, tanks, fuel pump hangers, fuel rails, pressure regulators, and even injectors are rusting within a year. Speaking from experience, go over the fuel system. Nothing worse than entering a 12-24hr race and doing 30 laps, being under the hood the rest of the time. :(

[Camper Van Someren]

The water pump is behind/beside the timing belt, so it's right there anyways, and typically we do them at the same time, along with the tensioner - also a good time to check/replace the cam/crank/intermediate shaft seals while there. Go ahead and pull it apart and see what's in there. More than likely you have rust blocking passages, and all your freeze plugs will be paper thin. I had a motor sitting in a crashed race car, stored inside the shop for 2yr, took it out to replace the one in the endurance car, and the night before the race checked it with the coolant pressure tester, sure enough - freeze plug burst! Had to change them in the car, in situ, all 11 of them, was there until 4am. That was NOT fun. The fuel system will also need to be gone over. Fuels today aren't very combustible, even after a single year, and adding the 10% ethanol, tanks, fuel pump hangers, fuel rails, pressure regulators, and even injectors are rusting within a year. Speaking from experience, go over the fuel system. Nothing worse than entering a 12-24hr race and doing 30 laps, being under the hood the rest of the time. :(

Thanks for the input. I’m hoping the fuel system isn’t too gunked up since he drove it every few weeks. But I’ll look through that next. The coolant system is full of nasty rust sediment, and all of the hose nipples on the thermostat housing are corroded. I’m sure this is the reason for the bad water pump. I just got a kit to replace timing belt, water pump, thermostat, cam oil seal etc. Thanks for the tip about the freeze plugs. They all look pretty good, probably switched out when this engine was installed 4ish years ago. Any tips on how to see if they are good from the outside? Just tap on them to get a sense for thickness? This one next to the drain plug is the only one that looks questionable, I’ll have to keep an eye on it once I get coolant in.

[Camper Van Someren]

Surprise! Although my car is an ‘86 325es I found a VIN on the block from a ‘90 325i.

Talking to the previous owner, he said he had swapped in a new engine 4 years ago but the car never seemed as fast afterwards. He said he tried to use the new fuel system but it would barely run so he swapped all of the old accessory parts onto it. He never changed the ecu, and it has all of the pulleys, sensors etc added back on from the eta. I know this is suboptimal and I’m losing lots of power. No wonder it seemed slow, only revving to 4600.

Anyway, I plan to give it a shakedown on track as-is, then swap the ecu and accessory parts to i parts to get the extra power. Currently I’m doing the timing belt and water pump, but the old pump seems to spin just fine.

1) if the car had symptoms of a bad pump but it is really ok, could this be related to pulley size? I know the i and eta had different size pulleys and if this affected tension, maybe the pump wasn’t spinning? Is there any way to tell the i and eta pump and crank pulleys apart so I know which type is currently on the car?

2) when I put it back together after timing belt, I’d like to put an i harmonic balancer on so that I don’t need to switch that part later when I change the ecu. Problem is my car already has a CPS there that was reading the non-toothed balancer. I know the primary cps reads the flywheel - the manual says this one on the front is for diagnostics only. Question is, can I put the i balancer on and either leave the diagnostic CPS or just disconnect it? Will that affect the way it runs?

3) noob question: I’ve read on here that one i part I’ll need to switch is the “air fuel module” but I’m not familiar with this. Searching for M20 AFM just shows me the mass airflow sensor. The more I read, it seems that the AFM is just the black box on top of the MAF sensor and these parts are swapped together. Is this true?

I’ve learned a lot from various threads on here (I even read all 500 posts on the 2.7i sticky since it seemed relevant) but couldn’t find answers to these questions. Thanks for any help!

[ForcedFirebird]

The eta CPS is just a diagnostic aid and only is wired to the diag connector near the manifold. It has no function for the ECU, so for all intensive purposes you can eliminate it all together.

The pulleys on the eta and b25 are different, but match when using the proper crank damper. The b25 uses a larger diameter WP pulley, but a smaller diameter crank pulley (all 6cyl m20's used the same fan belt part #). The only issue is when mix-matching and a non-standard belt needs to be used.