Monday, September 25, 2023

My 1981 BMW 320i: Update #2

 Rebuilt top end of engine, and all timing hardware (plus bumper tuck)

The cause for starting this job, was because I had puffs of blue smoke on startup, or coming off of idle. This is a sign that oil is getting past the valve stem seals, and into the combustion chamber. the seals were most likely original, and brittle after 40+ years. The right way to replace them, is by pulling the head off. So I decided to replace a whole list of gaskets, seals, and hoses, since I was going to be disassembling quite a bit. .....It begins.....


Engine bay before
 


Engine bay after



Hood off, bumper off, up on jack stands. Ready to start work.



Radiator and hoses removed. engine looking oily and grimy



Water pump and belts off.



End of the crank shaft with the pulley removed.
The seal must have leaked for a long time, it's down right fuzzy, in this area.



The Bosch K-Jetronic connects the air filter to the throttle body.
It's is dirty with a lot of oil, inside and out.



A rat's nest of fuel and electrical lines between the cylinder head, and intake manifold.



Intake manifold removed. Now to try again to get the fuel injectors extracted.



This was my diagram for reassembly, of how the electrical harness was threaded though the intake runners. Going to the starter, fusebox, and other solenoids. It's sort of a vertical cross section of the engine through the intake runners on the drivers side of the block.



Looking in cylinder 1 intake port.
The rubber injector seals were so hard, and old, I had to pry up with a large screwdriver, to get the injectors to pop out.



The inside of the manifold was coated with oil, so I had a shop chem wash the inside,
and media blast the outside.



The K-Jetronic
before.....oily



After..... cleaned up



Valve cover off, starting to remove timing components.



Timing hardware:

I replaced the cam sprocket, timing chain, chain tensioner, chain tensioner spring, chain guide, oil pump sprocket, oil pump chain, crank sprocket (...interference fit, so I used a torch, and a gear puller, with impact, to get it off), and baked the new one in the oven, to slide it on.




Looks like the old cam sprocket has some teeth wear compared to new.



Using a photo to note what top-dead-center looks like on the distributor.



Head removed. Here is a view of the top of the combustion chambers on the head.
Two valve with lots of carbon everywhere.



The top of the block, with the pistons covered in carbon




Cleaned the aluminum pistons slowly with a scotch pad, and WD-40,
to remove all the carbon.



This aftermarket 4-1 stahl header was installed by a mechanic, years ago.



Notice that whoever installed it, had the exhaust gasket backward,
causing a bottleneck of exhaust gas flow for #4



Cleaned carbon from the flange, for reinstallation



Cylinder Head:

I removed the head and had a machine shop disassemble and rebuild it. It's an aluminum head on an iron block, so the head was decked, (I think they took off 6/1000s ") and given a 3-way valve job. They replaced the valve stem seals, and valve springs. They cleaned it, and chased all threads. They also chem washed and media blasted my intake manifold, which had a coating of dirty oil on the inside, as I didn't know how I would get that clean.


Rebuilt cylinder head back from machine shop


Upper and lower timing cover ready for media blasting, and painting with engine enamel.



The crank seal had evidently been replaced at some point.
Looks like the mating surface had been gouged with a screwdriver, attempting to remove the seal. I would not be surprised if that was the source of an oil leak.



When I installed the new seal (using a PVC pipe as a drift) I used HondaBond on the mating surface to prevent any oil from making its way around the outside of the seal.



Below are all the parts that I media blasted (with the manifold exception) and painted.
Valve cover
Upper timing cover
Lower timing cover
Alternator bracket
Oil dip stick
Coolant Y-pipe
Oil filter housing
Intake manifold
Crank pulley
Water pump pulley
Water pump (new)
Harness bracket



Oil pan had to come off to access oil pump.
That was a good reason to replace the oil pan gasket.



As far as I knew, my existing fuel injectors worked fine.
However, I bit the bullet, and replaced them anyway, for $189




I decided to replace my under-hood insulation, since the hood was off.
 the original foam insulation was brittle, and would dissolve when pinched between fingers.

Old, torn insulation on underside of hood.



New self-adhering foam insulation with foil bought off of Ebay, and cut to size.



Bumper Tuck:

I had wanted to do this mod since I bought the car, but haven't got around to it til now. It involves taking off the bumper, removing the hydraulic piston mounts, drilling them out, draining the hydraulic oil, compressing the piston, and reinstalling. This brings the bumper about 3-4 inches closer to the front end.






I also checked and adjusted the aim of my Bosch fog lights





List of all the parts I replaced (some labor) and the costs:

Cylinder head rebuilt + chem clean intake mani   $1,020.36 
Intake manifold gasket   $24.09
Exhaust gaskets   $24.89
Fuel injector seals   $46.03
4 Bosche Fuel injectors   $189.64
Grounding straps   $23.44
Electrical connectors   $12.99
Valve stem seals   $19.31
Valve cover gasket   $13.39
Valve springs   $159.35
Timing cover gasket   $11.68
Water pump & gasket   $39.68
Banjo bolt copper washers 22 ct.   $24.14
Fuel distributor gasket rings   $18.43
Head bolts   $71.61
Head gasket set   $67.18
Radiator mounts   $15.97
Timing chain   $43.45
Oil pump chain   $32.56
Oil pump chain sprocket   $39.80
Chain tensioner   $27.29
Chain tensioner spring   $1.51
Chain guide   $7.78
Cam sprocket   $53.95
Crank sprocket   $15.38
Oil filter housing gasket   $14.88
C-clip for rocker arm   $13.09
Curil T2 -NAPA (gasket maker)   $21.50
Oil pan gasket   $18.67
Water pump to return tube - hose   $18.55
Water return pipe   $71.00
PVC hose (discontinued)   $46.20
Rad hose 11531266956   $20.17
Rad hose 11531266454   $13.97
Rad hose 11531266453, 11531267971   $57.23
Underhood insulation   $38.64
Cold start valve hose   $19.09
Brake booster hose   $12.99
Coolant hose, head to inlet   $18.59
PCV hoses   $13.88
Vacuum hose (1 meter)   $9.98
Coolant hose (1 meter)   $19.22
Spark plugs   $34.48
Oil cap   $21.00
Oil filter   $11.55
Fan belt   $25.10
Air filter   $20.99
1 gallon concentrated coolant $15ish
5 quarts oil.  $25ish
Coolant drain plug washer   $4.20

Machine shop, and parts total    $2,588.87


I took it to an automotive shop to get a once-over, when I was finished, to confirm everything was running optimally.

Ignition timing
I specially wanted them to look at my ignition timing. It seemed to run fine. ( I could have gotten a timing light and attempted to check it myself, but I didn't feel like adding that task to the mix, at this point.) They said it was a little too advanced at 2200 RPM, so they adjusted it.

Air/Fuel mix
I may have found and eliminated a vacuum leak when reassembling vacuum lines, so I had them check my air/fuel ratio, which I thought could be too rich. I don't own an exhaust gas analyzer, so I wasn't going to do this myself. They confirmed it had an A/F ratio of about 9:1 (too rich), they adjusted the K-jetronic to bring it into proper spec at 14.3-14.7 with a 950 RPM idle.

Valve adjustment
I adjusted my own valves, but the valve train seemed noisy, so I asked their opinion, and they ended up doing my valve adjustment again.

Small vacuum leak
They also found a small vacuum leak and tightened some bolts down to fix it (apparently not uncommon with these engines.)

Mechanic total $789.37 (4 hours work)

Grand total cost $3,378.24



Conclusion:

The duration of this job was from Thanksgiving '22  to end of summer '23. (I had a lot of periods of inactivity, as I did other things, or waited for parts from Europe)

It has only been about a month, but it seems to run and drive well.

I am pleased with the total cost. I have no doubt this would have cost at least $15-20K to have a shop do all the work that I did.  I am planning a road trip soon to Door county, Wisconsin to enjoy the fall colors, and test the car out at length.

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