Coolant leak above A/C compressor pump?
 

I noticed a small coolant leaking coming from my car the other day. I got it up on the ramps and pulled the plastic panels off of the bottom so I could get a better look at where it's coming from.

The leak is on the passenger side of the motor, right above the A/C compressor pump. I can't see where it's coming from, from the top of the motor...everything looks fine. Underneath the car, I can just tell that it's running down the block, and dripping off of the bottom of the A/C compressor.

There are no coolant lines in that area.....what could be leaking? I was wondering if anyone had any ideas before I started pulling the front of the car apart to get to the leak.

After looking through some pictures I found online....I'm guessing this is my issue. There is a coolant blockoff plate on the block......I'm guess these plates can leak over time? I'm also guessing that I'm going to have to pull the entire front of the car apart and take the supercharger off in order to get to it??

Here is a picture....it's that plate on the left had side.

https://cimg5.ibsrv.net/gimg/www.nor...9d09f76f59.jpg

Interesting, they designed the engine so that coolant could be introduced on either side. Hopefully you don't have a leaking head gasket. On real OEM they actually show the plate being mounted where the water pump flange is. Part numbers below

The o-ring is:

Part 11111487596 was found on the following vehicles:

• MINI R50   (09/2000 — 11/2006)
• MINI R53   (09/2000 — 11/2006)

Would that be because this engine design was shared with other makers, such as Chrysler/Dodge?

The engine was a joint effort between Daimler Chrysler and the Rover Group. Thinking that it was more D-C than Rover to start out as the Rover design was too big. Yes the Tritec was used in the European Neons and I believe some Chinese cars as well.

What I find odd is that the RealOEM schematic has the engine depicted with the flange/o-ring where our water pump flange is.

Somewhere here is a thread by an Engineer that worked on the engine development.

Not as fast as I used to be. The two ports are there as the Justa's water pump is driven off the belt and therefore would be logical that the coolant enters the engine on that end.

Also moving to the Stock Problems/Issues area. One more item that our Gen1s are going to face as the years add up.

freeze plugs
 

The cover for these holes are called freeze plugs. If you google it you will get a lot of old wives tale as what they are for - like allow the frozen coolant to expand so not to damage the water jacket if you are too cheap to buy coolant. The more likely purpose is for emptying out the sand after investment casting process of the engine block. Do you know why its called investment casting?

That cover plate is not a freeze plug.....it's covering up the port that is used for the "just a coopers" ....they use that same block.

Freeze plugs did not have bolts holding them in place that I am aware of and definitely not a rubber o-ring. As noted in two posts above, the passenger side port is for the Justa.

I am just learning more about our engines here, and find a lot of these fascinating especially in surveying photos of many 4-cylinder engines of different era. I would say they are both "freeze plug" for aiding sand casting as well as designed to accommodate the same block for different cars' packaging constraints. There are two freeze plugs on the other side of the block.

The more important function of the freeze plug port is for strengthen the sand mode during pouring. Most of the cast iron block of the same era I checked have similar freeze plugs. What is interesting is the later era aluminum blocks most has no freeze plugs. It is possible that AL is much lighter and requires less support. Also most has open water jacket at the cylinder top face which gives a lot of structural support for the cylinders during casting. The need for lateral support during casting is very similar structural challenges of cast concrete in construction.

late focus aluminum block has cylinder top open water jacket openings
https://cimg0.ibsrv.net/gimg/www.nor...1bd5a36416.jpg

freeze plugs on the other side of R5x block
https://cimg4.ibsrv.net/gimg/www.nor...e4605e582b.jpg

R5x closed water jacket openings
https://cimg2.ibsrv.net/gimg/www.nor...70b4d9226f.jpg

Learning these stuff (how its made) is fascinating. When GM first formed Saturn, the company made a big deal about their innovative use of ESP foam forms for engine casting instead of wax.

Did wee bit of concrete work in my days; forming, placing, pulling a screed and finishing. There is an art to the proper vibration of concrete as unlike cast metal, the material does not want to flow into tight areas.

Yep one engine with multiple was to fit into one chassis. Those plates like to leak over time. https://www.northamericanmotoring.co...name-help.html

There is some great info here on the development of the Tritech engine here. Tritech developer posted up.

https://www.northamericanmotoring.co...oper-here.html


It's a good read.

What's the easiest way to get to that plate in order pull it off and reseal it? Can I pull the AC pump off from the bottom of the motor and get to it underneath that way, or do I have to pull the entire front of the car off and remove the supercharger in order to get to it?

Its really tight under there, you would have to have small hands to reach it. If you are doing the supercharger or water pump repair then take the front end off as you are doing that anyway.

So it's possible to get to it and remove it from the bottom but going up where the AC compressor is? That's an hour long job........that's going to be much easier than pulling the front bumper, radiator, intercooler, throttle body, and everything else that needs to come off in order to get to the supercharger. ......That's a full days job.

I just need to know if it's possible........if there is physically enough clearance to get the bolts out of the cover, or it they hit the supercharger. I can overcome the big hands issue :lol:

Might be able to jack the engine up like you do when the putting a sc pulley on. The PIA is getting the bolts in place and I have thought in the past of taking something like a candle, drill it out so that the bolts passes and sticking it to the plate. Get the plate in place, start the bolt and then use a soldering gun to melt the wax.

The supercharger is pretty snug to the block at the location of the leaking cover plate. I highly doubt that you'd be able to get in there (with tools or hands) to remove it with the S/C in place.

If you haven't yet done a supercharger oil service and/or water pump replacement, now would be a great time.

With 160,000 miles on the stock SC...not sure I really want to mess with it at this point. I don't know what an oil change would help it out any.....

I guess I might just drop the AC compressor first, just to see if I can get to the plate. It's just a few bolts. If not...I guess I'll start pulling the front off of my car :sad:

Its not that hard of a job at all. Pull the front of the car off and pull that supercharger! At 160k I'll bet that the fluid is worn and brown or maybe in less of a quantity than there should be. It's the first thing I did when I purchased my current R53.. You can then address the coolant issue, and the leaking crank sensor o-ring, etc...

It is not difficult at all.

Watch this guy:

No need to reinvent the wheel. Heck he can pull an engine in an hour. After watching his video I did it in 2 hours- (I had lots of beer breaks though) :)

I think I have a similar coolant "leak." I'm in DC (near 0 degree temps for the last few days. I had the clutch replaced about 3 months ago. No leaks. The Tech offered to replace my coolant but I said no.'

Anyway, a couple of days ago, after not having driven it for a week, I drove to work but didn't heat up the engine first. Lost about 4 oz on the garage floor (didn't notice until I returned from work) and more on the road (spewed along the bottom of the engine case). I sucked out about 8 oz of coolant and put 50/50 mix back in. Did much better (less leakage). I also compared the color of the leaked/sucked out coolant. It was weeeeaaaak. I think over the last two years, a reservoir swap and a radiator swap, as well as living in New Mexico, the coolant was diluted to the point of its inability to prevent freezing in single-digit/teens temps.

I also cut a piece of cardboard the size of the A/C "radiator" and slipped it in place between it and the bumper. Made a HUGE difference in coolant temp jumping all over the place. Before, it was jumping from 165 up to 180. Talk about a cold drive to work. Afterwards, I had a nearly immovable 184 degrees and the car heated up nice.