Pulling Engine Block Drain Plug Yields No Drainage

As I noted in my prior thread on "Electrolysis" (No Stan, we are not discussing the cosmetic removal of unwanted hair!) -http://www.e9coupe.com/forum/showthread.php?t=18182 - I am in the process of replacing my hoses, tstat and water pump.

In that thread, I posted a picture of the water separator/tstat housing in part because of the corrosion on the tubes, and in part because of the somewhat rusty color inside. Moving right along, yesterday I pulled the engine block drain plug and to my surprise, nothing at all exited the engine block. In addition, the plug is not even moist; instead the plug looks dark and dry and black, sort of like a spark plug with carbon fouling:



From this picture, there was clearly coolant remaining in the system:



Here is a picture of some grunge on the front of the water pump, which I removed spilling coolant all over the engine bay and the floor:



And here is a picture of the block where the water pump was pulled. That brownish color in the coolant passages (which is somewhat washed out by my drop light) looks like rust to me. Note there is still coolant in there, even though the block drain plug is out.



I was planning on merely putting a hose in the head and running water through it for a while, but that plan involved drainage out of the drain plug.

With the brownish color inside the water separator/tsat housing and on the front of the block, the grunge on the water pump impeller, and the fact that nothing drains when I pull the engine block drain plug, I am concerned about whether I may have a blockage within the engine coolant passages somewhere.

Thoughts on how I should attack this?

I use a piece of coathanger wire or a small pick.
the block is above the hole usually.
Go in and up.

... and then be prepared to get a coolant shower in your face.

Every time....hahaha

Thanks a ton guys.

Chris, looks like you are taking advantage of the winter weather to do some great repair and maintenance. If you're looking for any parts don't forget I have some odds n ends so let me know if you need anything that I might have. I'll be up your way in March- let's get together!

Outstanding! PM me with dates; would love to get together.

Peter Coomaraswamy said:

Chris, looks like you are taking advantage of the winter weather to do some great repair and maintenance. If you're looking for any parts don't forget I have some odds n ends so let me know if you need anything that I might have. I'll be up your way in March- let's get together!

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If you guys are going to get together, pls let me know. I'd love to join you, if I'm around...but I'll be away at Amelia Island and BMW Classic Florida Tour from March 11-22.

I am thinking that with my coupe in pieces and both of Peter's coupes in Austin, you may have the only working coupe in such a gathering!

Doug Dolan said:

If you guys are going to get together, pls let me know. I'd love to join you, if I'm around...but I'll be away at Amelia Island and BMW Classic Florida Tour from March 11-22.

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Doug, looks like it will be a miss- I'm up there from March 13-15, Chris, did you get the hairball out of the drain plug as SF Don suggested? Just wondering as I will be doing that to the Polaris coupe while the engine is out.

Not yet; was traveling and just returned.

Peter Coomaraswamy said:

Doug, looks like it will be a miss- I'm up there from March 13-15, Chris, did you get the hairball out of the drain plug as SF Don suggested? Just wondering as I will be doing that to the Polaris coupe while the engine is out.

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I've had one car over the years with this same issue. We typically change coolant every two years in the northern climate of New England, BMW Coolant and distilled water.
We only eliminated the problem on this car after we removed the cylinder head and were able to access the block water jacket directly. After this we have changed coolant on this car annually.
What we found was a layer of deposited rust along the entire length of the block on the exhaust side. This needed to be loosened with a long pick and flushed out.

A lot of work, I agree, I hope yours doesn't require this level of effort!

Mario L.
VSR1.com

Thanks Mario -- I too am a big fan of regular coolant changes and use BMW antifreeze exclusively. I know the antifreeze was changed eight months ago just before I bought the car; before that the car sat for about six years, and best guess is that distilled water was not used previously. Who knows.

Based on our discussion last week, I plan to evaluate my engine and use that data to determine next steps. The date on the head indicates it is not original to the car so my engine probably was overheated and repaired at some point. I want to make sure I have good compression before deciding how to proceed.

Mario L. said:

I've had one car over the years with this same issue. We typically change coolant every two years in the northern climate of New England, BMW Coolant and distilled water.
We only eliminated the problem on this car after we removed the cylinder head and were able to access the block water jacket directly. After this we have changed coolant on this car annually.
What we found was a layer of deposited rust along the entire length of the block on the exhaust side. This needed to be loosened with a long pick and flushed out.

A lot of work, I agree, I hope yours doesn't require this level of effort!

Mario L.
VSR1.com

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So, a buddy of mine lent me a borescope, which just about shot the entire day yesterday. What a cool toy.

Anyway, here are pictures of my engine drain plug:





The stuff blocking the opening is really hard. I tried scraping on it with a screwdriver and an ice pick and barely scratched the surface.

I'm worried I may not be able to resolve this with the engine in the car. ugh.

Tap it with a sharp chisel and hammer.

Go ahead and hit it harder with a punch and a hammer .. .BTDT . . .no where as much force as what needed to install freeze plugs.
Aim your punch up, just be careful to not strike against threads of block drain hole.

Mario L.

Wow" that is quite a plug! Is it magnetic? I would be afraid to knock that into my engine. It looks carbon ish?

I like the bmw coolant because it matches the colour in the logo
Why does everyone who doesn't stock bmw coolant say it's ok to use modern-regular phosphate free or multi-vehicle coolant. What is your opinion?

Don't know much about the properties of the crud in my engine yet, other than the fact that its pretty damn hard.

As to concerns about knocking it into the coolant passages and then flushing them, if you have a suggestion for extracting that junk without pushing inwards, I am all ears.

I have always used BMW coolant in my BMWs, and not because of the color. I believe it is probably true that other coolants will effectively cool the engine, but the problem is that the process of changing to a more generic coolant might lead to a chemical reaction between the two coolants inside the engine. That's why I stick to the BMW stuff.

What's the history of this engine? Was it running well and not overheating prior to the attempted cooling system flush? I'm going to advise that you try only to create thru flow of the blockage at the drain plug. The rusty debris that has caused the drain to be blocked could be a layer of rusty sludge along the entire bottom of the cooling jacket along the side of the engine block. Dissolving this and circulating it with a running engine could leave you with a faulty T-stat, blocked heater core, blocked flow passages to cylinder head and a blocked radiator.

I am not a metallurgist, and don't want to suggest a chemical treatment that would not be compatible with the aluminum and other metals in a BMW cooling system. Copper and brass along with solder amongst those.


So there's no magical solution here. My suggestion of poking the stuck crud inward is to create a flow patch so fluids inside can drain out. This might possibly carry other loose debris along . .

Another thought, haven't done this myself, but it might work, use a right angle drill with a small drill bit and drill through the debris. It's likely only 6-8 mm thick. The spiral drill would then carry out particulate vs knocking it in.
Which ever way you choose, make certain the cooling system is full of water and vented to allow for draining once a flow path is established.

Mario L.

Hi Mario - thanks again for jumping in here.

I got into this car in June; it was running and had not been overheating. Now that this issue has arisen, I do recall thinking the heater was warm, but not really hot, the one or two times I used it.

I have only run the car for approximately 250 miles since I bought it. The plugs do not indicate that any of the cylinders were overheated.

As I have said several times, triage on this car has been a bitch. I had intended to attack items directed toward reliability, starting with the electrical and cooling systems.

I attacked the electrical system first, spent a chunk of time on melted wires and fuse block and light housings and whatnot. I also installed Euro headlights while I was at it. Wiring is intact, battery is new, alternator works well, grounds are now good, lights all work.

I also redid the front suspension to address a clunk (caused by a bent bolt holding the front control arm to the subframe that was not entirely tight), in part because sometimes scarce front control arms became available, and in part to address sloppiness.

Next up was the cooling system, to include all the belts. In the process of pulling off all the hoses, belts, water pump and tstat, I discovered the grunge and the blockage.

Prior to my ownership, the car had been sitting for six years. Not sure about the quality of the care prior to that, although the owner claimed to love the car.

The block had one ground; from the a/c bracket to the fender housing. The alternator to block ground was a wimpy little wire to the oil filter housing and the ground from the tranny to the firewall is missing. Also, the prior owner had a big aftermarket stereo installed, which had been separately grounded (and improperly fused, causing my melted electrical component problem). I mention this because I believe either the wimpy grounds or stray currents coming from the improperly grounded stereo could have contributed to electrolysis (or galvanic corrosion or whatever) within the engine.

One other comment on the engine; the original head was replaced with a head stamped 1979. I believe this is better than the original head, but not as good as the heads after 1980.

I first posted about the corrosion when I pulled the hose off the water separator/stats housing, and found corrosion on the housing and a rusty color inside:



There also appears to be rust on the block where the water pump had been installed:



There also was some serious crud on the water pump itself:



The gooseneck on the back of the head looks a lot like the water separator.

I appreciate the suggestion of the angle drill. I had already been thinking about that because with the engine in the car, there is little room to swing a hammer and drive a punch or a chisel into the blocked hole.

Here again, I had been planning to try to get a handle on the inside of my engine once I got the coolant out. I borrowed the borescope in the hope of looking into the coolant passages to see if I can evaluate the situation. That plan, however, is dependent on getting the coolant out of the block and that, in turn, is dependent on unblocking the drain plug.