Milky Oil

I had to leave the country for 2 weeks for a funeral, and while I was out, my son called telling me how he had a bad hose and was leaking water. He said he tried to patch it with duct tape to get by. To my horror, he said he was close to home and the car stalled. A police car ended up pushing him home the last 1/4 mile.

Next day he took my car so he could buy a hose at the dealers. He replaced the hose and drove the car and he claimed it was fine. Couple of days later, he said the car started running rough and the oil was milky. Exactly what I feared.. So instead of coughing up money for a tow, we're looking at another big job and potentially very costly. Very stupid. So angry.

So there are 2 probable causes... 1. Head gasket.. 2. Cracked head

If we remove the head, would I always be able to find a crack in the head? Is it possible for me to think the head is OK and miss a crack? Is there anything I should do beforehand?

Peter

Cracks can be very tiny and easily be looked over.

Typically, when you bring the head into a machine shop, they can pressure test the head in order to make that determination. Always best to seek out a machine shop that is familiar with BMW heads.

alan

Yep, let the machine shop check it for cracks, they pressure test and use that pink and green spray stuff, forget what it is called.
I know these BM heads do not like heat, but that said, they are as tough as nails, probably just a gasket, you get away with a skim and bolt it all together.
But I would check and make sure.

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.

We removed the head yesterday and at first I was hopeful. The internal surfaces of #4 was oily and #5 was rusty. I thought it might just be the gasket. But my sons friend who works at a auto shop was able to spot the crack.

That being said... need a replacement head or another car. Given that my son already wrecked one car and ruined this head... I'm not about to get him a car... He can get a job and get his own.

Now I started doing a search and I see that there is a "casting number" 1705885 on the head and it also says 2.5/2.7 (liter)

I found a head ($450) that looks identical however it says it's from a 528/530 (link to head).

Do you guys know anything about the 2.5/2.7 marking on the head? Is this head for both 2.5 and 2.7 liter engines? Is it for E30's only?

Regarding the oily cylinder #4... I suppose it could be a worn piston ring, but it seemed like there is too much for a worn piston ring... Leaky head gasket?

Any comments?

I looked up the "casting number" and found this in Wikipedia... M20B25

Applications:

1986–1994 E30 3 Series
1989–1990 E34 5 Series
1988–1991 E30 Z1

So these vehicles all use the same head it seems.. then I see:

The 2.7 L M20B27

Applications:

1982–1987 E30 325/325e/325es
1982–1987 E28 525e (or 528e in the US)
"In cars produced from September 1987, the eta engine got a substantial refresh from the factory. This included the more recent Bosch Motronic version 1.1/1.3 with adaptive idle control and revised circuitry, the "885" head casting with the larger valves, ports and revised combustion chambers"

So am I correct in assuming that I could use a E28 head (assuming it's the same casting)?

While I am no expert in decoding BMW heads, is it possible the casting number just relates to the blank casting before it is machined and cam installed? Is there a way to determine that the same head was indeed used in both vehicles? You could try going to a BMW repair shop for info or contact Pelican Parts to see if the parts are indeed interchangable.

alan

Thanks, Very good point..

I didn't think about the cams/valves being different.

I just spotted a head for $325 on eBay in my area...

I also saw another head (same casting) which said:

BMW 2.5 325, 2.5 525 Rebuilt head 87-90 #1705885

So maybe 325/525's are interchangable?

The casting number does not mean much to you, it is the part number that you need to check.
Why not go to Real OEM and check the numbers of the two and compare.
I would guess the oil is from the blown gasket, if you say there is too much oil to be rings, then surely you would have had issues with fouled plugs and poor running on that cylinder.

----------------------------------------------------------------------------------------------------------------------------------
E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.

Good point. It the part is identical and interchangable, it would have the same part number. Also realize, a head can have the same part number and still install a different camshaft.

Research will be key here.

alan

I have 2 friends, one was a factory BMW tech and the other guy works at the BMW Prep/Delivery depot in Oxnard, Ca. The second guy knows the cars A-Z, he is a great trouble shooter. I can check with him if you need me to.

The other question is can the guts of the head be re-used/moved to a new casting or do they also need replacing. Often times, cams and valves should also be replaced if you are going that far into the engine (at least in the Chevy V-8 world), not sure if the same applies to BMW.

alan



Edited 1 time(s). Last edit at 08/23/2010 10:13AM by alanrw.

OK, just got off the phone with my buddy the BMW tech. The heads are somewhat interchanable. You want the new head if not rebuilt to be rebuilt by a reputable machine shop who knows what valves go in your particular application. You can re-use your old cam and attendant parts. The machine shop will install new cam bearings as part of the head overhaul.

As was stated above, it is in your best interest to go with a machine shop that is familiar with this setup, they will know where the bodies are buried on this one.

There are Pick A Parts around, many of them will give you a few days guarantee to get the head inspected for cracks. If the head isn't cracked, now it becomes a rebuild project at the machine shop.

Ebay is somewhat risky as unfortunately, some sellers will say anything in order to close the deal, at least with a machine shop, there is accountability.

Good Luck

alan

Quote
sdp
I had to leave the country for 2 weeks for a funeral, and while I was out, my son called telling me how he had a bad hose and was leaking water. He said he tried to patch it with duct tape to get by. To my horror, he said he was close to home and the car stalled. A police car ended up pushing him home the last 1/4 mile.

Next day he took my car so he could buy a hose at the dealers. He replaced the hose and drove the car and he claimed it was fine. Couple of days later, he said the car started running rough and the oil was milky. Exactly what I feared.. So instead of coughing up money for a tow, we're looking at another big job and potentially very costly. Very stupid. So angry.

So there are 2 probable causes... 1. Head gasket.. 2. Cracked head

If we remove the head, would I always be able to find a crack in the head? Is it possible for me to think the head is OK and miss a crack? Is there anything I should do beforehand?

Peter

Hey Peter

I don't know what model/year your car is but the 2.5 and 2.7 heads are different. All the guys are giving you good advice. Usually the cracks in the heads can be found around the cam bearing towers; sometimes you can run the car or pressurize the cooling system and see coolant ooze out. I was away on holiday, I would've suggested that.

Be careful using old parts in a fresh head, work with a machinist for this...

Rick

Quote
sdp
So maybe 325/525's are interchangable?

This probably doesn't need answering at this point, but I actually know the answer so I'll jump in

The 525i from '89 to '90 (E34) used the same engine as the E30 325i, the M20B25.

As a side note, a BMW that I didn't even know existed apparently also used the M20B25. How did I not know this car existed before now?!
[en.wikipedia.org]

I seriously recognize every BMW after about 1965 or so, and know the model number for half of them... Had never seen a picture of that car until now.

Okay, back on topic!

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

Hi all,

So I have a couple of heads I've found locally. Some have said to look up the part number of the head (i.e. RealOEM), but the problem there is that the part number is not stamped on the head.. Most people selling the head go by the casting number on the side. I also see that there is another number (in my case) "91" with 2 dots.. I assume that means Feb 1991.

If I search the web with the "official" part number, I do find plenty, but they are usually listed with head shops and are $1000 on up... I have no intention of spending that much money. I think my best bet is with a local guy selling one with the same casting number but a "87" (1987)... My car is a 1990.... and then take it to a shop to be checked out.

Peter

Peter, it is only a "best bet" if it is the right head for your car. I understand your need to adhere to a budget in this case but realize, your engine and ECU are developed as a unit. Installing the wrong head could create a lot of headaches for you. For instance, again, I am not an expert on BMW heads. but if you get a new head with additional lift on the cam, with the wrong pistons, you could destroy the engine. For all I know, the head you have picked out will work fine, but again, research is key here. A bargain head that doesn't work with your car becomes scrap aluminum.

alan

From 1987 (325i- 2.5 liter) should be the same head as the last year; 91-92 325i (2.5) as far as I know... Rick

Half an E30! I see them once in a while. Collectors item, quite expensive!

Quote
Michiel 318iS
Half an E30! I see them once in a while. Collectors item, quite expensive!

Michiel, you are very quick; one would not know that English is not your native language

So, when I sell my iX, I will have to make sure I include both halves in the sale

English, German, French, Dutch, whatever, just don't sell your iX! Unless you let us buy it. (group buy anyone?)(oh yeah, I've got the room to store it dry)

Still miss my iX!


And I was reacting to the Z1 Earendil didn't know of yet.



Edited 1 time(s). Last edit at 08/27/2010 12:39PM by Michiel 318iS.

Here is a discussion about M20 heads.

M20 Heads

A shop advertised on Craigslist a like new head for $200 except it was the 1264200 casting. Their mechanic said it would work on my 325is but the redline was lower and power was lower.

I think I'll stick to the 885 casting and get one in Aneheim for $230.