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[QuickSilver 0]

Hi everyone.

After a continuing struggle with my motor, I have decided to post up too see if I can get any thoughts that could help me identify this. I am at a loss at what to do and I have already invested money into this and really would like to find out what it is before I pull the motor apart. Again.

The story so far:

As some of you know (well most) I swapped my old m20b20 out for a m20b27. The motor had suspected head or head gasket problems, but I went and installed it risking it anyway. I knew the risk I was taking and what it could/would lead to.

The motor ran without signs of any problems for about a month, when one of my routine fluid checks showed up oil in the coolant tank.

So, off came the head. I went and got the head pressure tested which revealed a crack underneath the cam, not the typical m20 crack thats normally under the cam, but it looks as though at one time the head dropped a rocker and it punched into the lobe underneath the cam, there is actually an indent from where the crack originates. The head was most likely rebuilt without doing a pressure test - not good!

So, not being on the biggest budget I decided against repairing the head I would buy a new head (well second hand) because in my opinion a repaired head is not as good as a not cracked head in the first place. After organized a really good condition head which was known to be fine, I decided to get into it. Picked up all the parts from Gavin at EuroItalian, and put it all back together.

Re-assembled motor with new head bolts, head gasket, cam belt, tensioner, oil, filter, spark plugs and coolant. Pretty standard in my opinion.

It all came back together without hiccups aside from me accidentally destroying one head gasket. (locating dowel stuck to HG and pulled it off)

The head bolts that I bought are Hex type stretch bolts. The sequence for tightening these is;

Initial 30nm -> 90" degrees -> 90" degrees.

Motor started second turn, ran well, bled fine, heater blew hot air and car temperature didn't budge bast 1/2.

Satisfied I took it for a decent drive, went and picked up my partner from work, and went to visit a friend, being happy to simply be driving my e30 again. I did not expect any performance improvements, but I did notice that the car accelerated smoother, most likely due to the fact that the head was in better condition than the one that came off.

Came home, without problems, finished the night in a good mood.

The next morning:

I decided to flush out the cooling system one more time to clear out any left over oil/gunk left in there.

Now is where it gets damn f**king annoying. Motor will not under ANY circumstances bleed, there is pressure build up in the cooling system once the motor gets hot. Some strange symptoms.

Heater obviously does not heat up because it never gets all the air out, not all the pipes were heating up, so I assumed that I had bad timing and my thermostat died a bad death. Replaced that. No luck.

The motor will get to operating temperature, but the water in the coolant tank stays stone cold. It then gets to a certain point, where all of a sudden it comes back up through the pipes and pushes all the hot water out of the expansion tank. I cant see any water circulating. - I find these symptoms very weird, especially with the water in the coolant tank not getting hot at all ( until it gets forced back, thats when the hot VERY hot water gets pushed out )

It will build up a lot, and the bleeding screw will whistle like a kettle on a stove, even once I turn the motor off, it takes a while for it to stop whistling. If when the motor is off I then remove the expansion tank cap, the water gushes out and all pressure is released immediately.

The motor does not over heat despite all this, and I have not had it over heat on me even with the old head on there.

Took my car down to my local mechanic who very kindly hooked the radiator up to a pressure tester, it was reading higher pressure in the cooling system. - I would not put it past this guy to live under a big flat rock, he does not know BMWs or euros for that matter, and stretch bolts seemed to be a new phenomenon to him. So I don't know what to make of his diagnosis.

So we come back to the beginning. Head gasket, block or head. This is a totally different problem than I was having before but can be caused by the exact same things.

Before, there was a leak from the high pressure oil chamber into the water, it was so slight that back pressure from the radiator was NOT enough to force water into the oil, only oil into the water when the car was running.

Now there is a leak from the combustion chamber into a water galley.

I have tried various things, I am more inclined to lean in the direction of the head gasket. Maybe out of hope, but also because I scrutinized the head around the combustion chambers and water galleys and because I trust who I bought the head off whole-heartedly.

Have pulled the spark plugs out to see what they can tell me. But their not talking

I don't understand what has happened here, the most confusing and frustrating part of it all, is how great the motor felt that one night, without problems. The motor did not over heat in that short time.

Just to throw it in there, the block is in good condition. And I highly doubt this is the issue. I still think it lies with the head or head gasket.

So I guess this leads me to a few questions,

These are torx stretch bolts, I know how they work, I know how to torque them, but does anybody OUT OF PREFERENCE or experience tighten these once the motor has been run, even if the specs don't specify this?

Does anybody have anything that they can offer? I think I have nearly exhausted everything, but someone may have something I haven't thought of.

I do NOT want to use a product like Iron tite, for one it wont fix Head gasket leaks, and even if it fixes something its such a band aid fix I cant live with it in my conscience.

I am super tight about how I do things, I am not one to rush things and I take my time to do things right, this was not a rush or botch job.

Thanks for reading my novel

Pre Facelift E30 1987

m20b27

ETA bottom.

"885" or 325i head.

4 Door

5-Speed manual.

Just to confirm for those who don't know, motor is of course running motronic 1.3

Note: water pump less than two months old with a METAL impeller.

Before you ask, the previous head was also a 325i or "885" casting head. There is no issue with fitments etc.

Edited October 29, 2008 by QuickSilver

[Boost Junky 1]

So with the new head on the oil is pushing through into the water? Did you get the new head plained and the block skimmed, sometimes it pays to have the blocked skimmed so I have been told so dont quote me on that.

As far as your air in the cooling system goes, I have the same problem simply because I dont have a bleed valve lol..

I simply fill my cooling system up with radiator fluid and water, wait for the thermostat to open then pump the air out by squeezing the bottom hose until I feel a constant flow of HOT water flowing through the hose and the reservoir is fill to the top, somehow it manages to get all the air out of the system and my motor never overheats etc. I know im not running the same engine but cant be to much difference...

Luke

[QuickSilver 0]

So with the new head on the oil is pushing through into the water? Did you get the new head plained and the block skimmed, sometimes it pays to have the blocked skimmed so I have been told so dont quote me on that.

As far as your air in the cooling system goes, I have the same problem simply because I dont have a bleed valve lol..

I simply fill my cooling system up with radiator fluid and water, wait for the thermostat to open then pump the air out by squeezing the bottom hose until I feel a constant flow of HOT water flowing through the hose and the reservoir is fill to the top, somehow it manages to get all the air out of the system and my motor never overheats etc. I know im not running the same engine but cant be to much difference...

Luke

The oil pushing through into the water was the problem with the OLD head. Thats in the bin.

The new head or gasket seems to be leaking pressure from the combustion chamber into the cooling system, so it is constantly introducing pressure, so it wont ever bleed.

I've had no problems bleeding it in the past. This all started the following morning after its first run.

[Boost Junky 1]

Ahh I see. So im guessing you did carry out standard procedures when replacing the head? Plaining the head and cleaning the old gasket off the block etc...

So the head is 100% legit as you have tested it correct? You sure theres no hoses or gaset leaks in the thermostat housing... or maybe a hose to your heater? Im sure you would know two check all that but cant think of what else it could be?

No water galleries blocked? Hope you sort this out, I know how frustrating these things can be!

[QuickSilver 0]

Ahh I see. So im guessing you did carry out standard procedures when replacing the head? Plaining the head and cleaning the old gasket off the block etc...

So the head is 100% legit as you have tested it correct? You sure theres no hoses or gaset leaks in the thermostat housing... or maybe a hose to your heater? Im sure you would know two check all that but cant think of what else it could be?

No water galleries blocked? Hope you sort this out, I know how frustrating these things can be!

The block was planed not long ago. The head I did not get tested because I knew where it came from. I know people will flame me for this, but I am not made of money, and after purchasing the head and everything else it starts to really add up.

The head was thoroughly cleaned, and block was equally cleaned, all the tops of the pistons, it was spotless, I would have performed open heart surgery on both surfaces.

The hoses or thermostat leaking would not cause such a huge pressure build up, they'd just leak water. The hoses to the heater are not block either, as far as I can tell the electric valve is opening also. Even if it wasn't this would not account for this problem, it would simply bypass the heater, there would be air in the heater core but becase the valve wouldn't be opening it wouldn't matter.

I have considerd a blocked water gallery. But how do I check? How do I find out? If it were blocked I could understand possibly how the pressure is building up, IE water pump constantly pumping water and slowly building up back pressure.

Thanks for the input Luke.

Edited October 29, 2008 by QuickSilver

[OLLIE 26]

I don't think the problem is the head or head gasket. it could be a blocked water gallery, but it would take a bit to fully block one.

it sounds like the cooling system needs a bloody good bleed, also i'd check that your viscous fan coupling is sweet and the fan is spinning properly. I'm sure you know this but with the engine running fill the water right up till it comes out the bleed screw, keep topping it up until all the air is out, closing the screw every so often to let pressure build up. leave the heater on full etc ...

did you put the thermostat round the right way?

strange symptoms indeed for an m20

[QuickSilver 0]

I don't think the problem is the head or head gasket.

it sounds like the system needs a bloody good bleed, also i'd check that your viscous fan coupling is sweet and the fan is spinning properly. I'm sure you know this but with the engine running fill the water right up till it comes out the bleed screw, keep topping it up until all the air is out, closing the screw every so often to let pressure build up. leave the heater on full etc ...

did you put the thermostat round the right way?

strange symptoms indeed for an m20

Have checked viscous. Have tried to bleed the car several times, have tried many different methods, have tried to flush the whole system out. Thermostats were all put in the right way. I even punched out the center valve on one to test if all my thermostats were busted, but even this "temporary" fix didn't do anything.

The system wont expel all the air, and I think that at some point during the process the water is starting to turn to steam.

The water is not getting around the motor. This I know because the coolant tank water does not go into the motor and stays stone cold until it backs up, I am in conflicting thoughts about this, because even if the Head, or head gasket was leaking into the cooling system, the water should still be circulating, and atleast all of it should be heating up.

In regards to a blocked water gallery, there was oil sludging around the cooling system with the water.

Edited October 29, 2008 by QuickSilver

[*Glenn* 854]

This is exactly the same problem that this engine had when it was in the other car and I did the pre-purchase inspection on it.

And yes...I will say not the best to put a head on an engine before having it professionaly checked first. Even though it may come from a very respected seller. It still should have been checked.

We have been having trouble with non genuine thermostats doing that on E30's and vehicles with M50 motors. Have you tried a genuine thermostat ?? I dont know why , but some of the non genuine ones dont work.

You obviuosly have a flow issue, which can really only be thermostat, water pump, headgasket, radiator or a restriction in one of the main cooling hoses. Are you also sure you put the head gasket on the right way ? It should have been marked on the front.

BTW: M20 engines are also known to crack blocks under severe overheating. I doubt (hope) its not that. From your description..I still think its a flow issue. An infa red temperature tester may help to identfy where the flow issue is located.

You dont retighten torque bolts. And the tightening sequence you used is correct

Edited October 29, 2008 by *Glenn*

[QuickSilver 0]

This is exactly the same problem that this engine had when it was in the other car and I did the pre-purchase inspection on it.

And yes...I will say not the best to put a head on an engine before having it professionaly checked first. Even though it may come from a very respected seller. It still should have been checked.

We have been having trouble with non genuine thermostats doing that on E30's and vehicles with M50 motors. Have you tried a genuine thermostat ?? I dont know why , but some of the non genuine ones dont work.

You obviuosly have a flow issue, which can really only be thermostat, water pump, headgasket, radiator or a restriction in one of the main cooling hoses. Are you also sure you put the head gasket on the right way ? It should have been marked on the front.

BTW: M20 engines are also known to crack blocks under severe overheating. I doubt (hope) its not that. From your description..I still think its a flow issue. An infa red temperature tester may help to identfy where the flow issue is located.

You dont retighten torque bolts. And the tightening sequence you used is correct

Thanks Glenn, the thermostat I have is genuine, the one that I thought may have failed was no genuine so I threw that in the bin. And as I mentioned also tried the fix where you remove the centre valve, just to be sure. No luck there though.

As far as I know I did install the head gasket the right way, all the markings were in the right places and it sat on the locating dowels, if I remember correctly any other way and it would not sit properly.

I am going to go through the motions soon and take off all my hoses again, check them, and check the radiator.

Is an infa-red temp tester common equipment for a mechanic to have or do I need to have a look around?

Thanks again,

Alex.

Edited October 29, 2008 by QuickSilver

[*Glenn* 854]

The testers may not be a tool a mechanic might have. However a technician would have one as a vital diagnostic tool.

I now cant see that it could be the hoses, heater or radiator. Because the engine had this problem in the other car. You only purchased the engine... correct ??

[westy 614]

Seeing that the engine had the same problems in 2 cars suggests the problem is in the block yes?

Maybe the block has blocked gallerys that caused the problem with the previous head??

Are you sure the block and head are compatible?

[antony 0]

Did you use a b25 or a b27 head gasket? (are they different?)

[QuickSilver 0]

The testers may not be a tool a mechanic might have. However a technician would have one as a vital diagnostic tool.

I now cant see that it could be the hoses, heater or radiator. Because the engine had this problem in the other car. You only purchased the engine... correct ??

The problem it was having earlier was slightly different. There was pressure entering the cooling system via an oil chamber. The leak was oil -> water.

The old leak was very small, as I mentioned above. Once the car was off, the pressure inside the radiator/cooling system was not enough to push water back through the crack into the oil. The oil only escaped into the water when the motor was running and a huge amount of pressure was going through that chamber.

Now its from the combustion chamber to water gallery. No fluids are mixing, the leak is different.

Also the motor never did this when the old head was on, it did have a leak into the cooling system but it was not enough to affect it bleeding or running fine.

I pretty much purchased everything in the engine bay. Complete motor loom, all ancillaries the whole shabang.

The head and the block are compatible, I used an b25 head gasket, it has an 83mm bore which is the same as 2.7, checked all this out.

Edited October 29, 2008 by QuickSilver

[*Glenn* 854]

Sorry, you are wrong. The engine did do that when I checked it. Thats why I told the prospective buyer not to buy it.

I'm also still thinking it maybe a block issue, or something you may have done effecting flow in the cooling system

[QuickSilver 0]

Ok, I did not know it did this thing then too. I thought it was just the one leak.

Why would it run well for one day and then this problem surface? Any ideas?

By technicians what do you mean? Where would I go to have this check performed? I would rather know EXACTLY what the problem is rather than guess and shoot in the dark.

What else could I have done to hinder the flow of the cooling system this badly?

Edited October 29, 2008 by QuickSilver

[*Glenn* 854]

Yes it did this after you drove it... it over pressurised and had signs of oil in the coolant.

If you havent done anything wrong, it must be an issue with the block or the new cylinder head

BTW: A "technician" is a mechanic with a brain and the right equipment to carry out a repair proffessionaly

[Hartage 0]

I have had this same thing with 325 motors, just wont bleed properly. Have you tried putting a hose into the heater pipes and turning it on very slowly on a cold motor with the filler cap on, to push the air round the system to clear it?

I have done this to two cars that over heated like you are saying , ( one of them Penrys ) to fix an air lock that i could not get out. Worked a treat!

Ok, I did not know it did this thing then too. I thought it was just the one leak.

Why would it run well for one day and then this problem surface? Any ideas?

By technicians what do you mean? Where would I go to have this check performed? I would rather know EXACTLY what the problem is rather than guess and shoot in the dark.

What else could I have done to hinder the flow of the cooling system this badly?

[QuickSilver 0]

I have tried to flush it out with a hose yes. No avail.

[tibbs.james 1]

From your first post...

"The motor will get to operating temperature, but the water in the coolant tank stays stone cold. It then gets to a certain point, where all of a sudden it comes back up through the pipes and pushes all the hot water out of the expansion tank. I cant see any water circulating. - I find these symptoms very weird, especially with the water in the coolant tank not getting hot at all ( until it gets forced back, thats when the hot VERY hot water gets pushed out )

It will build up a lot, and the bleeding screw will whistle like a kettle on a stove, even once I turn the motor off, it takes a while for it to stop whistling. If when the motor is off I then remove the expansion tank cap, the water gushes out and all pressure is released immediately."

My car did this to me after it got up to temperature, it got close to but not on RED on the temp gauge then all of a sudden pushed all the water out.

The temp rose in a fairly sudden burst.

I then did a full head rebuild and gasket set and this issue was solved, i found on my head gasket it had not been sealing at cylinder 6 and you could see where the gasket was damaged and allowing gasses to enter the water system. I had no oil in water what so ever with my M20B20

I did not use a genuine Thermostat, and my engine did bleed correctly. My engine always run at 1/4 temp warm with 3 different thermostats.

One thing i have always done while the head has been off on an engine is get the air compressor into all the coolant channels and give em a good blast, where a surprising amount of crud comes out and hits you in the face.

[williams 0]

dumb question-when u fill the coolant/water and start the car does the water squirt into to bottle from the small breather pipe?if not then the hole might be blocked it is very difficult to clear this problem(8mm pipe to a 2mm hole in the bottle) ,and u say that there is alot of air when u bleed it afterwards-this will also not show the correct temp on the gauge as the gauge needs water to supply the right temp reading- so all in all if the bleeding pipe is blocked then ur car will have these symptoms

[Yamahoo 6]

Interesting thread, I guess not so much when it's your car! I'm also suspicious of a cracked block or a failed head gasket. If you're pushing compression through to a water gallery, even very slightly, it can affect circulation in some pretty weird ways. And then it can give a false read on your temp guage, which is only reading the local temperature around the sensor, which of course is irelevant if you don't have circulation. In cases like this you can have the water boiling and steaming in a localised area in the system, which makes it practically impssible to bleed, because the compression keeps pumping air ito the system, even if it is a miniscule amount and not enought to be showing up in major blowout though the radiator. Most decent workshops will have the gear to test for exhaust gas in the radiator, which might be a good place to start to see if you can rule it out or not.....

I may be well off the mark, and for your sake I hope so. We always like to hope it's just a plumbing issue or something simple.........

[Yamahoo 6]

Hey, I just read your original description again. I presume you've run it with the cap off and checked for bubbles/gushes? And with an open thermostat (or thermostat removed) and the cap off and you've watched for circulation through the radiator? I'd be starting right there if you haven't.

[QuickSilver 0]

Well everybody it looks as though I have sorted it out. I held off on posting this until I'd be a little more sure. Yesterday after a trip to see Glenn, I got home to try a few things. Re-routed one of the hoses which was pinched, tested the thermostat was opening and at the correct temperature and spent a long time filling up the cooling system properly and trying to get it bled as much as possible BEFORE I turned the car on.

Car bled first try and have had no problems since. Drove last night for about 1 hour and 45 minutes constantly checking and re-checking everything, today I braved a long drive in all conditions, hard, soft and motorway. No problems, have driven a good 150ks and have had no issues.

So, as far as I can see it was a bad airlock, the thermostat that WAS in the car wasn't opening and the one I've replaced it with is working perfectly, plus its genuine bmw.

Problem solved! Thanks for all your input everybody, thank god it turned out to be something simple.

[westy 614]

The ooooold pinched hose trick eh?

You'd be relieved that was all it turned out to be.

[OLLIE 26]

another couple of hundred k's and you can put some antifreeze in.

glad to hear it was a simple fix albeit frustrating to diagnose