Thermostat and Water Pump Corrosion

[CCE36]

Hello

So I recently bought an 1997 e36 with an M44 engine. I bought all new OEM parts to do the recommended cooling system overhaul but when I go and remove the water pump it was REALLY STUCK. I had to get a pry bar and a friend with a mallet to be able to get it out. Finally we got it out and to our surprise there's something that looks like corrosion on the inside of the case. The coolant that was inside the car was kind of muddy and green. So I guess I want to know if my engine is damaged and or what can I do to clean it on the inside if at all possible. I'll try to attach some pictures.

Thank you in advance for any comments

[spyderg0d]

Carrosion. From useing tap water instead of distilled in the coolant. Also possibly from any sort of stop leak anyone would of ever used. Or, just normal 20+years of oxidizing.

[shogun]

do a coolant flush with citric acid powder or vinegar, Mercedes Benz even has that with a part number, just for info: Cooling System Citrus Flush https://dieselgiant.com/mercedes_citrus_flush.htm

[thenjnick]

I would also say to flush it. Drain it from the radiator and from the plug in the block down under next to where the exhaust headers are. If you really want to get most of it out fill it back up with distilled, run it and drain again


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[CCE36]

IMG_20191127_201439.jpg IMG_20191127_201427.jpg IMG_20191127_201429.jpg


Here are some pics. Finally got home and was able to upload them

[thenjnick]

Definitely flush it, rust and corrosion will do that. Wipe out what you can reach. Maybe take a look at the heater control valve and flush that as well before you have any problems with it. You might consider some additive like shogun suggested, its the best you can do really but it should suffice.


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[Eric93se]

Whatever flush chemicals you decide on, be sure to use the block drain plug to get it out. Maybe wise to flush with distilled after doing the flush .

[jmo69]

Get the proper coolant right away, BMW, Pentosin or Zerex G48.

[gdavid]

Flushing it out is pretty straightforward. It should go without saying but cleaning up both areas to allow for proper sealing should be your biggest concern. The thermostat housing looks like it should dress up pretty well with some light sanding, be sure to use a flat backing block when you dress it up and be careful to keep it square to the surface so the edges don't get rounded. In some cases the mounting surface of the thermostat housing can end up with some pretty significant voids that need to be filled in (JB Weld is a go to) but yours doesn't look too bad.

At the water pump mounting, the smoothness of the inner, cylindrical surface is most critical to allowing the water pump's oring to make a good seal. This can be dressed up with 600 or 800 grit wet dry sandpaper, be careful to sand evenly around the whole perimeter to keep it round although as ong as you stick to that fine of sandpaper, it would be pretty hard to screw up.

Flushing it out is pretty straightforward the corrosion and buildup is pretty common on any 20+ year old car with questionable coolant added at some point. While the heat transfer is less efficient with build up inside the cylinder and engine block it isn't a common source of failure, most of these engines overheat due to lack of coolant due (catastrophic loose of coolant when old cooling system parts break or lack of adequate bleeding) and not just running a few degrees warm due to poor heat transfer. Pressure testing the system is a good idea prior to re-installing your belts and fan and filling the system up.

[jclausen]

Use jb weld to fill and sand smooth

[CCE36]

Awesome. Thank you for your answers. Ill get to work right away.

[B320i]

Definitely get onto it before you wind up with a corrosion hole somewhere expensive... Like your cylinder head.
Use OEM coolant or an equivalent with the same additives. It's late here, but off the top of my head that means something along the lines of Phosphate, Nitrite and Amine-free. Change it completely every other year (i.e. same time as your brake fluid). What's a few dollars in a good-quality coolant versus thousands for a cylinder head or new car?

How you flush is up to you - some use a garden hose to physically push fresh water through (obviously draining it all before replenishing with good coolant), whereas others will drain and refill with some additive before draining and refilling again. Just whatever you choose to do, don't cut corners. Do it once, and do it right.

A mechanic once told me that distilled water is actually corrosive - although the stuff marked as such here in Australia has a small blurb along the lines of "deionised water product" which makes me think it's just filtered water. Personally I might stick with premixes in future.

[Eric93se]

No, don't use regular water, you won't get it all out. A gallon of distilled water is less than a $1, you wouldn't need more than 10 gallons to flush with chemicals then with distilled again, then with proper mixture. A properly serviced car will not have that corrosion, you have to use distilled water and change the fluid every few years depending on what the bottle says. Rmeuropean has a couple different BMW type antifreeze, I've used Fuch's and Zerex. You really should only use flush fluid that is meant for the cooling system, there are a ton of them, no reason to mix something up that may do damage.

[jmo69]

These pics are of the m54 in my e46. I've been pretty good about keeping the proper coolant in it. It may have had Zerex G05 in it when I bought seeing as the coolant was almost clear. I did put some green in for a short time but has been OE blue ever since.

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[Franky goes]

I just went throught this when I had to replace the head gasket because corrosion at the bottom of the head broke the seal.
I was anal about replacing all the cooling parts preventively and ended-up with coolant that turned acidic from sitting in the block too long.
The comment from my trusted indy and the guy who reconditionned the head was to do a full coolant flush, including the block, every 4 years regardless of the coolant replenishing while servicing any part of the cooling system in the interval.

There was no internal rust like you but the water pump and thermostat housing were massively corroded even if it is aluminum. The most difficult part of the head gasket job was to get the thermostat housing to not leak. Got it after 3 attemps. Ended up using permatex coolant sealant bead.
Next time the plan is to use JB Weld as described before and replace the aluminum housing with the OEM plastic part that has a gasket on all the surfeaces and replace it every time the thermostat is changed.

I always use distilled water and 50/50 mix of the BMW coolant.
A coolant flush every 4 years is now on my list of preventive maintenance... $1,000 later.

My 328 has 420,000 kilometers on it and it's a winter car.
If you decide to keep your car for the long haul flush the entire system evey 4 years.

In your case I would flush the entire cooling system, run it for a couple of weeks, replace again, and again a year later or until the rust is mostly gone.
That is if you want to keep the car for some time.

[Eric93se]

Be careful suggesting jb weld and the thermostat housing. Even the OP's pics don't warrant any filler. If anything a paint stripper wheel could be used to take off the buildup, if there was good access (I'm not referring to a metal wheel) .

[B320i]

I just went throught this when I had to replace the head gasket because corrosion at the bottom of the head broke the seal.
I was anal about replacing all the cooling parts preventively and ended-up with coolant that turned acidic from sitting in the block too long.

This is basically what's happened to me recently. While the coolant was partially replenished quite a number of times with cooling system work done progressively over the time I owned the car (plus dumping the radiator and doing a partial change at one point), there's a 10yr gap in the coolant change history from 2003 to 2013; where it was changed just before I got the car. Wound up with a hole the size of my little finger in the back of the cylinder head. The corrosion in the water gallery was so bad it had exposed the bolts for the flange attached to the back of the cylinder head. If either myself or the Indy I visited for regular servicing had thought to stick multimeter probes into the expansion bottle to check for electrolysis, this disaster could've been averted.

So yes, change your coolant completely, often (BMW recommends biannual flushes) and with the CORRECT coolant.

[Eric93se]

Here's two different products that you could use. Maybe get both and run then at different times, be sure to pull the block drain plug after use.

https://www.amazon.com/Zerex-Super-Radiator-Cleaner-ZXC02/dp/B00J65INPO/




- - - Updated - - -

https://www.amazon.com/Thermocure-Co...dp/B00R74I5UY/

- - - Updated - - -

They also have Zerex G-05 antifreeze, full strength.

https://www.amazon.com/Valvoline-Zer...dp/B0033QNZZ0/

[jclausen]

I've used jb weld for this problem on many e36's and it works

[Eric93se]

This guy doesn't have any pitting, so he has no need for jb weld. He just needs to clean up the surface with a brass brush or non metal pain stripper wheel.

[Franky goes]

I had a section of the thermostat housing on the driver side that was pitted and was repaired with JB Weld.
The section of the seal on the passenger side looked fine but that section ended up leaking...
The aluminum housing also needs to be polished with wed sanding to make sure it seals correctly with the O-ring.
It can be one of 3 or 4 things. This is why I'm going back to the OE plastic with a gasket next time. It gets changed with the Thermostat.
The extra $20 is worth it to save 3 hours of trying to make the aluminum housing work.

[CCE36]

Hi guys! I was able to install the water pump and thermostat after cleaning the mating surface with 800grit.

I assembled everything and filled with distilled water. No leaks as far as I can tell except for the thermostat housing . I will need to replace that ASAP. This is branded Dorman, si I wont buy that again, what brand do you recommend getting?

[JDStrickland]

Hello

So I recently bought an 1997 e36 with an M44 engine. I bought all new OEM parts to do the recommended cooling system overhaul but when I go and remove the water pump it was REALLY STUCK. I had to get a pry bar and a friend with a mallet to be able to get it out. Finally we got it out and to our surprise there's something that looks like corrosion on the inside of the case. The coolant that was inside the car was kind of muddy and green. So I guess I want to know if my engine is damaged and or what can I do to clean it on the inside if at all possible. I'll try to attach some pictures.

Thank you in advance for any comments

I'm not getting what the issue is. This looks pretty clean to me. I see nothing more than simple surface contamination that is meaningless in any sort of diagnostic sense. Replace the parts you were going after, refill with the proper coolant and water mix, or just buy premix and be done. Your engine needs you to observe proper bleeding procedures. The 4 cylinder needs bleeding done properly to a greater degree than the 6.

[Eric93se]

Rockauto has several choices, if you're not sure go with the beck Arney.

[CCE36]

Hi again. So finally I was able to finally finish all the cooling system overhaul! It took me a while but I figured it out. That back coolant connector is a real BITCH to get out, mine was rotten and the screws where missing the heads, I had to break the plastic piece and melt it with a torch and then scrape it with a hot scraper, I did some REALLY good footage of the whole process because me and my friend used my phones flash while recording to be able to see what the hell we were doing back there. I'll try to upload it to youtube tonight or tomorrow and post the links here. I got some really good shots of the connector that I couldnt find anywhere!.

I started with a cooling system overhaul but found along the way some other things needing addressing, here's a list I made of everything that was replaced:

Engine Air Filter 13721247404 $20.28
Steering Joint 32311092949 $47.15
Front Driver Regulator 51331977609 $149.95
2 Emblem $19.95
Goodyear Emission Hose $12.99
Intake Manifold Gasket $17.79
Intake Head Gasket $18.09
Meyle Transmission Mount $16.83
Air Hose from Fuel Rail 13411247782 $25.97
Coolant Connector 11531714738 $27.95
Filter Cap $6.29
Door Clips $4.99
OEM Power Steering Pump USED $35.00
Sliding Clips Window $6.49
Filter Housing O-Rings 11421709513 $5.16*2
Magnetic Oil Drain Plug $12.95
Pioneer MVH-S21BT $37.60
Slip Ring $65.00
Oil Filter Housing Gasket 11421709800 $5.11
Engine Crankcase Breather Hose 11151247903 $22.31
Heater Hose Inlet Cylinger 64211394295 $9.67
HVAC Heater Outlet Pipe 64211387010 $8.79
Upper Radiator Hose 11531743535 $18.58
Lower Radiator to Thermostat Hose 11531247261 $13.59
Cabin Air Filter 64119069895 $9.68
Meyle Water Pump $43.57
Coolant Back of Cylinder Hose $9.89
Thermostat $38.06
Radiator to Pipe Lower Water Hose 11531743295 $15.99
Mahle-Behr Thermostat $34.20
Authentic Tail Lights $170.00
Thermocure Radiator Flush 2-Pack $34.99
Driver Window Regulator $149.00
Intake Tube 13711743320 $87.26

(had to buy 2 thermostats because I over-torqued and broke one housing and the case coolant connector I had a URO brand that wasn't flush to the plug so had to order an authentic one)

Now everything's Assembled and bled, applied the Thermocure to start cleaning everything in the inside. Heater works now thanks to the new HVAC. BUT when it gets to temperature it starts to ROUGH IDLE. I checked ALL hoses that I can see from the top and don't see anything. The car when is revved it runs great until it lowers the RPMs. So what do you think it could be?

I recorded a short video where you can hear it fail

https://youtu.be/r6Xos6bYHHw

Any suggestions would be great!