From digest.v7.n502 Mon Oct 27 23:42:24 1997
From: Jim Cash <j.cash_at_sympatico.ca>
Date: Mon, 27 Oct 1997 18:54:42 -0500
Subject: Head Failure - Eta Engine
For those who have an interest in a head failure on the Eta engine, the following is taken from one of the letters I sent to BMW AG
I removed the parts of the letter that were not related to the head problem.
As you can see I am replying to their first reply to me, in which they seemed to indicate that the problem might have been prevented by better maintenance.
I was trying to get to the root of 2 problems:
My only purpose in posting this is to give more background to other Eta owners who may have experienced the same "low coolant" conditions, or worse yet the head loss as some of you have.
Date: Jan 10 /91
To: ********** - Director Product Marketing, BMW AG
Thank you for your detailed response to my letter of Sept 19, 1990.
Regarding the engine failure, I may have caused some confusion by
the head failure and the need to replace the valve train. Attachment 1 provides a better explanation. My goal is to seek reassurance that, if there was an engine casting weakness, it has been recognized and corrected.
Thanks again for your assistance.
Circumstances regarding Cylinder Head Failure.
Your reply regarding "low coolant level/resultant engine damage" seems to indicate that the damage was totally as a result of my not stopping when the low coolant warning light came on. I fully appreciate that driving any distance with the engine coolant drained into the oil will cause damage. I have experienced coolant loss on other cars and in all cases the temperature gauge went up and I immediately stopped.
You stated that "regular and efficient maintenance" would minimize the
risk of such a reoccurrence. I may have given the wrong impression when
I said that "it is not unusual for the coolant level lamp to come on
since I have had a small leak around the water pump seal". The lamp has
come on 2-3 times a year since I bought the car in 82. For the first few
years I used to stop and check the level, however it was never lower
than the mid-line on the fill tank. This past year the lamp came on 3-4
Again the level was only low on the sensor. On one occasion I saw some drips on the driveway and found a slight dribble at the front of the water pump. The service manager felt there was no cause for alarm and if it got worse we would change the pump at the next service interval.
This combination of circumstances "conditioned" me to treat the coolant level lamp as a "reminder to top up" rather than a "warning" to make an immediate check. I can offer no explanation as to why I have had to occasionally top up the coolant over the years unless the head has always been a bit porous (I have never had to add more than 1 inch in the tank). I never noticed coolant in the oil, maybe since I change it so often.
I do not know if it is "normal" to experience small, gradual coolant losses however it seems reasonable that other owners may also experience minor losses that would cause them to also become "conditioned" to the level lamp. If that were the case, it would seem prudent to have a 2 stage level detector. The second stage should clearly warn the driver that a major coolant loss is taking place. I had relied on the temperature gauge for that warning, however your letter explains why I was wrong to do so.
The real issue, however, is the failure of the head. It was pressure tested under water and it leaks badly through the casting beside the intake valve guide at the 5th cylinder. As a (dubious) souvenir I kept the head, cleaned it up and put it on the shelf in my garage. My father-in-law has had a long career involving foundries and castings in Europe and Canada. He is experienced in aluminum alloy castings. I had NOT told him about my engine, however he was visiting and happened to go to the garage. He asked me why I had that head and whether I was planning to put it into the car (it was now clean enough that he thought it was new). When I asked "why he wanted to know" he said "it is a defective casting and will probably go porous". He showed me tiny bubble marks on the surface that he said would be throughout the casting. He explained various things that could go wrong in the pouring or cooling process that would cause this. I finally told him the story and asked why it would take this long for the casting to fail. Again, many detailed explanations regarding surface erosion and gradual porous leaks eventually leading to surface metal failure.
If this had not happened I would not have had to buy a new head. I do not see how regular maintenance checks would have prevented this. Due to the evidence presented to me by my father-in-law, and the fact that the dealer has had another head go porous on an E engine, I suspect there has been a problem.
Regarding the replacement of parts in the valve train. I was not
surprised that there was damage however I was told that some of the
parts had to be replaced primarily due to wear. The brass bushings were
worn on the rocker arm shafts and the rocker arms were quite loose.
Since I have always been very careful to change my oil & filter (I do it
times per year - avg 20,000 km/yr) I was obviously concerned about what would cause these parts to wear out so early. The only explanation the dealer could give was lack of lubrication at start-up. Therefore my concern about pressurizing the oil prior to start-up.
While there probably was extra damage due to the coolant in the oil for 80 km; the fact remains that the parts were worn out within 152,000km (At least 100k of which has been highway). You have reassured me that this wear was not be caused by lack of lubricant during start up and the dealer has reassured me that I have more than done all necessary maintenance.
Now that I know what did NOT cause the wear I still do not know what DID cause it. The "bottom line" here is that the head should not have failed and I do not know how to prevent similar early wear in my next car.
When this situation is coupled with the other problems I have had, you can see why I am still hesitant about purchasing another BMW.
Never dio get a definitative answer to the issue.