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Engine rebuild with no former experience........
- Racediagnostics
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Cheers
Jim
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1979 450SL - 2002 XK8 4.2
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- Racediagnostics
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Cheers
Jim
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- markus1971
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best regards Markus
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- Racediagnostics
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Cheers
Jim
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- Racediagnostics
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Engine lifted again.
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First task was to remove the trans oil cooler pipes.
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Then the starter motor.
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Spark plugs, not looking too good, especially No1 that has had the valve guide issue. They look like they have been running too rich but CO level is on target at 1%, so burning oil from somewhere.
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Transmission dip stick, tube, vacuum line and shift rod removed.
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Torque converter bolts removed via the starter motor aperture.
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Transmission bolts removed and lifted back off, but the torque converter stayed in place.
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Cheers
Jim
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1979 450SL - 2002 XK8 4.2
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The trans had been leaking pink fluid from the bottom of the bell housing last year till I put in some snake oil which seems to have fixed the problem. I'll replace both the shaft and pump seal though.
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I then locked up the crank shaft at the front to remove the flex plate.
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Rear cover removed.
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Crank seal plate removed.
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Finally the harmonic balancer bolt on the front of the crank. I bolted this lever on to the rear of the crank and asked Kim to stand on it while I unbolted the front, it came of easily.
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The first task tomorrow will be to fabricate a frame for this old TV to sit in to display the workshop manual in portrait mode.
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Cheers
Jim
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1979 450SL - 2002 XK8 4.2
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- Racediagnostics
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Has anyone used a sleeve here before?
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www.partsgeek.com/catalog/1980/mercedes/...t_repair_sleeve.html
www.rockauto.com/en/catalog/mercedes-ben...+repair+sleeve,10524
Cheers
Jim
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1979 450SL - 2002 XK8 4.2
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- Rudiger
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Just use some 10 weight engine oil on the inside.
Rudiger
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- Gullydeckel
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don't do that (now). Just install the new seal ring with 1 or 2mm offset compared to the former seal lip position.
I know from other engines, that for maintenance complete seal assemblies are offered where the seal ring is pressed in on a different axial position by manufacturer. Just to avoid the interference with the old running mark.
Modern seals are made from PTFE with a total different lip design and not produce marks like that anymore.
Best regards Martin
Ich bin jetzt in dem Alter wo ich meine Fehler zugeben könnte - wenn ich welche hätte
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is it possible to position the new seal just 1-2 mm off the former position? Doesn't the seal want to move back to its former position into the groove?
Regards,
Lutz
Nur wer für den Augenblick lebt, lebt für die Zukunft.
Heinrich von Kleist
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- wusel-53
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I think, it would be possible. When I changed the seal, it was so hard to get the seal in right Position. I can't belive, that the seal move back in the groove.
Viele Grüße
Thorsten
Man lernt nie aus
380SL (US-Version, Bj.84), Eura-Wohnmobil und ein ebike

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in this case you need an other Crankshaft-Seal. The Part-Numer ist A 120 997 02 46. This Seal has, in the same position as the old one, an offset of 1,5 mm at the main Lip.
Gruß Richard
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the seal lip design is very stiff in longitudinal direction and about 2mm are enough.
But this space at least must be available. At sealing diameters of this size installing a new seal at old position is not recommended!
Regards Martin
Ich bin jetzt in dem Alter wo ich meine Fehler zugeben könnte - wenn ich welche hätte
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Viele Grüße
Thorsten
Man lernt nie aus
380SL (US-Version, Bj.84), Eura-Wohnmobil und ein ebike

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Rudiger
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I did run into a problem today, two seized bolts, more details on that later.
In the mean time here is a video of the engine being removed.
www.youtube.com/watch?v=7Pb7fKt5dHY
Cheers
Jim
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1979 450SL - 2002 XK8 4.2
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Pulley and balancer removed, Someone has been in here before me to try to repair a front seal oil leak.
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The oil leak!
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Engine transferred onto the stand.
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Pulling the crank hub off.
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It has a deep groove also, someone had been in here before me and fitted a new seal which wasn't working too well.
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A look at the timing.
Crank on 0 degrees.
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Left CAM.
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Right CAM.
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With the left cam lined up then the balancer shows this.
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Cheers
Jim
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Water pump removed.
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Front of the engine stripped.
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OK, so here is the problem, there are two of the cap head bolts both at the rear of the intake manifold that are seized. As you can see they are long, I tried map gas and gentle pressure, then an impact and they stripped out.
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My plan is to weld on a big nut but from the way they felt I think the bolt will shear off at some point along the shaft. Because they are at an odd angle the manifold will not lift off if they shear above the level of the head.
Any suggestions?
Cheers
Jim
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Rudiger
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- Uncle Benz
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Mvh
Stian
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Cheers
Jim
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The one I had to cut off, I think I will be able to get this out fairly easily. Th good news is there was no damage to the head.
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The other side.
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The damaged intake manifold. It's not going to be easy to get the shaft of the bolt out. Once it is out, I will need to get someone to TIG weld the damaged area to repair it. There also looks to have been a bit of corrosion to the surfaces where coolant was washing against the surface and leaking under the gasket.
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Cheers
Jim
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Removed the rocker arms.
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This was a good investment.
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Next I decided to get the dip stick tube out of the way.
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It came out easier than expected.
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Then the tensioner.....
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...and manifold.
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Using a strong magnet to ensure the chain circlips don't go missing.
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Releasing the cam shaft bolts.
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Cheers
Jim
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1979 450SL - 2002 XK8 4.2
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Not much wear.
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Refreshing my memory before taking the heads off.
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First head, cylinders 5 to 8.
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Other head, cylinders 1 to 4, you can see cylinder 1 which had the valve guide problem has the most build up and is oily.
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Surprisingly, it also has the cleanest piston???
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The bores all look in reasonable condition with the cross hatching still visible to some degree.
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Curved guide removed.
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That's it for today.
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I did try to remove the front cover, all the bolts are out but it didn't want to come off so I will investigate more tomorrow. Perhaps the oil pan needs to come off first.
Cheers
Jim
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There were a few plastic bits in the cruddy oil at the bottom of the sump.
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Bits of chain guide rail.
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It is what it is.
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Oil pump off.
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I couldn't get the front cover off till I spotted this bolt.:doh:
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The lower chain guides which have never been changed in 41 years.
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The oil pump chain looks to be in good condition, all the links are tight so I wont replace unless there is good advice to.
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Timing cover with the idler wheel at the top and distributer cog on the left.
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Cheers
Jim
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Oil pump chain tensioner also 41 years old and worn.
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Measuring the big end end axial float and then crank axial end float.
Crank was 0.21mm vs limit of 0.3mm
Big ends were 0.29 to 0.33mm vs limit of 0.5mm
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Pulling off the crankshaft sprocket.
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Seven of the pistons were 91.99mm.
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Just one was 92.05mm, which is at the large end of the standard sized pistons.
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The last thing I did was remove the first big end bearing cap nuts, but the cap didn't want to come off. I gave the studs a light taps but it didn't break free. Any suggestions on how to free it off without damage?
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Cheers
Jim
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- markus1971
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very good ducumentation of your work, thank you for that. It will help me very much when i will exchange the chain guides of my engine.
Good luck for continuing the work,
Best regards Markus
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There is some slight scoring on the top side of the pistons, I was surprised that the underside was clear. Left bank viewed from the front of car.
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Right side.
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Main bearing sizes, only four shown but there are five bearings?
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Before removing the caps I made this video.
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Crankshaft lifted out.
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Cheers
Jim
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These two are the main over pressure release valve and the oil cooler over pressure valve.
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This one is the oil filer pressure relief valve.
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Cheers
Jim
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