Quick (Belated) Intro

[Gregory891]

As others have written, this variation in compression from cylinder to cylinder is normal. There is a specification, the rule of thumb I recall from when I played with 2002's and Bavaria's, is that no cylinder should be less than 20% than the highest one. You are FAR from this.

Leakdown test would also be a good test as well.

Before you take things apart, put a cooling system pressure tester on it. This will allow you to pressurize the system at say one bar (14 PSI) and see that it holds pressure on the gauge without the engine running. You can calmly look and see if there are any leaks. Aside the head gasket, these leaks would not be the origin of your overheating, but it's part of a normal, comprehensive cooling system check.

As for things to change, you have a good & logical list: full drain of coolant (at block and remove radiator), new thermostat, new water pump & inspect radiator for internal blockage / heat transfer problems. Water hoses are protective insurance for the future.

I would also suggest you check that the cooling fan's viscous clutch is working properly. Even a perfect cooling system won't work as it is designed if you don't have air flow.

[BimmerM3inGA]

Great suggestions! This forum is awesome, I'm glad I found it!

Can anybody point me to leakdown test and cooling system pressure test DIY? I've never had to do either of those before.

Question about draining the coolant from the block: How in the heck do you reach the drain plug? Part of the subframe and the driveshaft block access to it. I can see it, but am not able to reach it. Is there a trick?

[Rockit]

Mt 2 cents...my friend had the same thing with a 3.0 he bought not running. It was at the dealer 100 times for over heating and they never changed the water pump.

If it where me I would change the water pump and flush the coolant. I would send the radiator out to a shop and have it flushed and check for leaks. If your lucky the impeller fins are worn and that all it is. Yes the thermostat and coolant tank, change them too. These parts will have to be changed anyway at some point even if the head is not leaking.

My friend had to replace the head gasket because it was overheated and driven to far. The head was re-planed by a machine shop.. a must. He ran into a problem with the threads stripping out for the head bolts. The block when overheated does something to weaken the threads. He had to install new steel thread adapters made by BMW just for that, make sure you research and replace those too if it is the head.

From what you're describing the car was overhead and continued driving until the head gasket went. The head gasket repair was either done right or wrong? If the water pump was never changed...you should be able to see that...than maybe they never addressed the overheat problem. Just from what your describing I'll bet the water pump is fine and radiator and thermostat...if it were me I would change that anyway. I'll bet the heat gasket repair is not right...the head is probably warped and some bolts are striped. They probably wouldn't have abandoned a car with just a bad water pump. Even if it's a head, if you bought the car right it's still worth doing. Research those head bolt threads sold by BMW..I'll try and find out more from my friend. If you PM me I'll give you his number...he just went through all that.

[bcredliner]

I would like to know more about the overheating problem. When you checked the coolant was it low?

Even if it was not I think it was an excellent suggestion to pressure test the cooling system before replacing a bunch of stuff. Before I had that done I would have the system professionally flushed to get as much as of that--how to screw up a cooling system and not plug the leak crap, out. Armed with the results, I would start make cooling system decisions from there. I suspect the copper turd was for the cooling system only.

You mentioned evidence of water in the oil. What and how much evidence? The first place I would look for evidence of a blown head gasket would be oil in the water rather than water in the oil. Oil in the water looks like a foamy chocolate shake.

In your case evidence of water in the oil it may be a collection of condensation from sitting so long. Sitting that long, even with no evidence of water in the oil, I would change the oil and filter ASAP, cheap safety measure.

If you are concerned about the head do the suggested leak down test first. FYI--each cylinder must be at top dead center when tested. If one or more is bad, I would check the torque on the head before removing it so I knew if I needed to address that aspect before the head gasket is replaced. As suggested, I wouldn't replace the head gasket without having the head checked thoroughly beforehand.

[J.Belknap]

If the head gasket job wasn't right he'd see it in the fresh fluids after that is done. The bolts are torque + angle so all of them have different final values. I would leave the bolts alone.

Edit: recommend a simple drain / fill and go from there. IMHO, no reason to pull the radiator.

[BimmerM3inGA]

Thanks for all of the suggestions! I think the plan for now is to flush all the fluids and see what happens. I bought some cheap oil today for the first drain/fill cycle. Once I know the fluids are fresh and clean, I'll have a good baseline to work from.

I don't think I'm going to mess with the head right now. But I did bookmark the site for Time-Serts (just in case). But hopefully it won't come to that.

I have not seen any evidence of oil in the water, nor can I smell exhaust in it. The attached photo is what I mean by evidence of water in the oil.



The car had been abandoned for a year, but was not just ignored in a warehouse or something like that. It was at a repair shop and they occasionally had to move it around the parking lot. So it was started and run for a few minutes in order to move it. So the water I'm seeing could just be from condensation, as suggested. An oil change will tell me for sure.

I already planned to do a cooling system overhaul regardless. Given the age, mileage (140K), and unknown service history, that's a no-brainer. All that stuff needs to be replaced no matter what.

[Gregory891]

I've replaced BMW heads and head gaskets over the years and have seen real water in the oil. At worst, your dipstick pulls out and it looks like gray mayonnaise on it. Similar when you drain the oil.

If your drain looked fairly normal, most likely you had condensation from a year of moving the car a few car lengths with no warm up.

Do all the good things for the cooling system, even if you can't reach the drain plug on the block (socket extensions and U-joints may help).

Genuine BMW coolant or the BASF (from memory) OEM equivalent.

[BimmerM3inGA]

I had some time after dinner and played with the X5 some more.

I removed the water pump, thermostat and upper/lower radiator hoses.

Some observations:

The car has been parked and not run for at least 24 hours. When I removed the expansion tank cap, coolant gushed out as if it was under pressure.

The radiator is new. So is the expansion tank (date sticker says it was manufactured in February 2010).

The fan clutch is also new, but stamped "Made in China".

The water pump is newer than the engine, but doesn't look "new-new".

The thermostat and hoses do not look new.

It's apparent that somebody was looking for a cause for it running hot. But did they find it? That is the question!

I have a water pump, thermostat and expansion tank that came from another 3 liter M54 and are known to be good. They were replaced as a preventive measure, but were working properly at the time. I'll stick those in and fill it with BMW coolant, run it some and see how it does. I have new parts coming, but this will get me started until they arrive.

Does anybody have an extra water pump pulley they'll sell cheap? The one I pulled out has a chunk missing out of it.

Originally Posted by bcredliner

I would like to know more about the overheating problem. When you checked the coolant was it low?

No. I had already topped it off, but it was blowing past the cap on the expansion tank. If not topped again, I would imagine that it would quickly become low.

Question: Does the E53 use the coolant level sensor in the expansion tank? I ask because mine is not plugged in, but there's no warning light in the cluster. I can't find a connector anywhere in the area of the expansion tank that would plug into the sensor.

[bcredliner]

I have a 2002. The coolant level sensor is connected to a receptacle on the side toward the engine, quite close to the bottom of the expansion tank.

[bcredliner]

Excuse my post if you aware. The thermostat is controlled by the DME. DME software/hardware may be a problem. It should throw a fault code if it is haywire.