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Tuesday, July 14, 2020

Doug's Domain

Doug Vetter, ATP/CFI

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Monday, July 31, 2017

Cylinder Head Shipped

Today I spent only 30 minutes in the garage -- long enough to turn the head over to drain some of the oil that remained in it, inspect it for any obvious cracks, take the picture you see here, and then package it and the related parts for delivery to Autohead. I became frustrated that the box Autohead sent had clearly been through the shipping process several times. I used half a roll of shipping tape to ensure it wouldn't split at all the seams. I expected a new box, not one that had been through the wringer. What's that they say about first impressions? Strike one.

(Image: Underside of original head removed)

The package weighed in at 51 pounds and cost $76 to ship UPS Ground to Alabama. Simply because there was no room left in that package I put the springs, upper spring plates and new valve seals in another box which cost another $18. I almost never buy shipping insurance but given the cost of the parts I decided to add it. Considering my original estimate of $100 to send the head alone I figure I came out ahead. Autohead should see the boxes by Thursday, so the clock starts ticking late this week. I expect it to be returned in about 5-7 business days, but we'll see.

Technician Parts Analysis

Although I try to avoid seeing my technician on Mondays and Fridays (as if to imply that every day isn't crazy for him) I decided to swing by on my way through the area with all of the pictures I took yesterday on my tablet, as I figured high resolution pictures were the best way to allow him to inspect all the parts. What else can I say but: pinch zoom > glasses.

His overall opinion? The top end is very clean. He was also impressed that the cam bearings were in such good shape for the mileage. The implication was he had seen far worse at far less mileage (thank BMW and their stupid 10K+ mile oil change intervals). I then asked him for his all important opinion on the cam bearing scoring. He asked "did you fingernail test it?" I told him "not yet" and explained why. Surveying the damage he said "you'll probably feel some of these but most certainly that one", as he pointed to the E4 cap with the gouge in it. I then asked whether the fingernail method could be used as a pass/fail determination and he clarified that it's acceptable as a means to determine if it requires further attention (not that it needs to be discarded necessarily).

Unfortunately in this case, while it may be possible to grind the cam to smooth it out, the bearing caps really can't be fixed in any meaningful sense. I might be able to use some 400 grit paper to wet sand E4 to smooth it out a bit but that's about it. The scoring marks are simply too deep. Reviewing the last oil analysis I took back in 2015 I see that iron and aluminum were markedly higher. The comment on that analysis pointed to bearing wear which might have precipitated increased piston / cylinder wear. But iron also comes from camshafts and aluminum comes from cam bearings, so perhaps the analysis reflected nothing more than wear from multiple parts in a high time engine that is slowly self-destructing.

Looking at a picture of the timing chain sprockets he zoomed in on the teeth and pointed out how one side of each tooth appeared to have a more gradual ramp. His impression is that this kind of wear is typical and expected on an engine of this mileage. Obviously reflecting on the state of BMW engineering these days he summarized by saying "these engines were made of good stuff".

To wrap things up I showed him a picture of the two pieces I found lying in the head. They consisted of a metal washer wrapped in plastic with jagged edges. He couldn't place their origin offhand but based on the color we both agreed the most likely origin is the valve cover. Upon reflection I think they may also be remnants of the original valve cover gasket, assuming those have metal reinforcements. I'm hoping that's the case as a new valve cover won't be cheap.

Delivered Filter Kit

I neglected to bring a few parts with me to the transmission shop on Friday so I had to run the BMW filter kit and quart of ATF out to him today.

Why the quart of ATF, you're wondering? Frictions usually (but not always) are provided in the overhaul kits "dry", which means they must be soaked in ATF for several hours to allow them to absorb the oil. This is necessary to prevent burning the frictions during the first few shifts. The 4L30E requires standard ATF (Mercon) so any generic ATF would have done here, but I figured I'd provide a quart of the stuff I plan to use to fill the unit.

Next Up

I just got word that the driveshaft has arrived. I also have to place another order to get the parts needed to work on the body after I send the block out for machine work.

Over the next couple of days I plan to disassemble the bottom of the engine, inspect all the parts and begin the blueprinting process.