I didn’t want to take away from Alex’s cooling thread so I figured I’d start another one just on the 1990 BMW 325i coolant reservoir. Let me start off immediately with “if” you still have the OEM Throttle Body Heater plate then this mod isn’t for you as the BMW coolant reservoir doesn’t have the nipple on the bottom of the reservoir like the OEM LR unit. You “could” install a nipple where the coolant level sensor is, but that kinda defeats the purpose of this mod unless you just want the higher quality reservoir vs the much thinner OEM LR unit. Here are a few pics of the 1990 BMW 325i coolant reservoir.






It mounts the exact same way as our OEM units so installation is PNP. I will update this thread when I figure out how to wire in the coolant level sensor.

 

Wow! That's incredible how close that is. I can't wait to see it installed.

If one really wanted, you probably could add another nipple to the body. That said, TBH delete is the way to go.

 

do you double back your throttle body heater hose onto it's self or pipe it somewhere else?

 

With my current TBH delete I had a line running from the intake manifold to the OEM LR coolant reservoir. With this setup I plan on just plugging the intake manifold outlet and deleting that coolant line all together.

*On a side note* I just got done repairing two throttle bodies on two different Bosch V8's that the customer was trying to tell me was sticking on them. Both had TBH deletes and both complained it happened during our cold spells. One was on a 2000 P38 4.0L and the other was an 01 D2. I worked on them about 3 days apart.

On the P38 the throttle body was GROSS..... If you went full throttle and let go the gas pedal was rock hard and it would surge to WOT then stick again if released. I removed the throttle cable/cruise control and I had to actually pry on it with a screw driver to get it to pop free. If done by hand after releasing via the screwdriver, it was fine, but go WOT and release it and it would stick hard again requiring a screw driver to break it free. I removed it from the P38, sprayed it down with carb cleaner and it still acted up. In the mean time I had a spare TB laying around so I just slapped it in and sent them on their way. The D2 was a friends and it pretty much was doing the same exact thing! I was down to my last spare TB out of my parts truck so I tested it/cleaned it and got my friend on the road ASAP.

That left me with two sticking throttle bodies. After all that BS on the forums with cold & TBH deletes being the cause I wanted to see exactly what was going on! I cleaned them both very very good and they both looked clean, but they still would stick (D2 wasn't as bad as the P38's). I started with the P38 TB first. I removed the nut, the two cams with the springs, and cleaned and lubed it. Still stuck would stick when held at WOT & released. Then it would not open by hand. I squeezed the 3 screws holding the throttle body plate in place and removed them. The plate itself didn't look bad. I used a scotchbrite pad and really went to town on the outside edge. I also used the scotchbrite pad on the inside of the throttle body. After I was happy with them feeling smooth I re-installed the throttle body plate. Went WOT and released it and bingo it no longer stuck! I did the same thing to the D2's and now I'm back to having two perfect and extremely smooth operating spares.

I honestly think this could be some of the issues with sticking TB's that some people have complained about. I got both of them to look very clean with the carb spray however that did not actually fix it. Removing the throttle body plate, and using a scotchbrite pad on it's outer edge is what did the trick. So my thinking is the TB may look clean, but that doesn't mean it isn't sticking, and without removing the cables and doing it by hand you'd never know. I could see that and cooler weather really making it bad.

I'm still not a believer in the TBH being the #1 cause for sticking TB's especially when I know people in Canada, Alaska, and Wyoming, that have never had issues, but what I found with the two throttle bodies sticking so bad and looking perfectly clean after being sprayed and wiped down has me thinking you should remove the TB completely, spray it down, remove the throttle body plate, use a scotchbrite pad on it to ensure it won't stick at least once a year at least.

 

That's how I have mine. I used some 3/8" line and cut about half an inch off of a 3/8" brass punch to plug it.

 

Yep that's how I plan on doing it or while I'm working on the 4.6L V8 I have to install into my 04 (going to do HG/front timing cover while it's on an engine stand), I might take the intake manifold, cut off the nipple and drill/tap the hold and install a nice plug. It could be used for a future mechanical temp gauge as well. I'll end up with a spare intake manifold so if I jack it up drilling/tapping I can just slap on the 04's original.

 

Can't you just test the resistance on the BMW sensor against the LR sensor for variations? They both should work in the same manor -- When there isn't liquid to close the circuit, it'll trigger the sensor to be open aka light on the dash for low fluid.

 

There is no low coolant sensor on a 4.0/4.6L V8 D2

 

Great find! Cheers Best4x4!

 

Thanks Juke, I had some time to kill the other day so I just went to a junk yard to look around. They had a few older BMW's and I'm always curious to find cross reference parts. When I saw that coolant reservoir I was like BINGO lol.

It's not perfect for every LR (with TBH's intact), but you could remove the temp sensor, and find a cap that fit, and install a 90 degree nipple on it and attach the coolant hose. It's a very stoutly made reservoir vs the LR unit for sure.

The bottom nipple for the main line comes out straight vs a 45 degree angle, but I just test fit it in the 04 D2 and a simple piece of hose can fix that.