Pulled out my engine today

[OJCar]

You were lucky there!

 

[RaceDiagnostics]

My local suppliers only have 12.9 strength bolts in this size (vs 10.9), is it ok to use those?

 

[Melvyn Best]

 

[tom2207]

I had a bit of trouble with 6 of the smaller (M10) crankshaft bolts yesterday, they felt odd going in, so I pulled them back out this morning for inspection.

I take it the replacements are on their way ...

 

[RaceDiagnostics]

I ordered 12.9s as there are not so many 10.9 options.

 

[jenki]

Please keep up the story RaceDiagnostics your attention to detail is superb. I doubt I would have pulled the bolts for a check I think you dodged a bullet there keep up the good work.

 

[Wallace]

My local suppliers only have 12.9 strength bolts in this size (vs 10.9), is it ok to use those?

Do you have the torque specs, does it specify torque and degrees?

 

[RaceDiagnostics]

65Nm with no additional rotation. They only got to about 60Nm then started to give way on 5th use.

Original build.
Checking the original bearing measurement with crank out.
The bore measurement.
New bearing measurement.
Final assembly.

Manual says nothing about single use.

 

[Gareth_16V]

Does the manual state to assemble dry or with lube under the heads/on the threads, and with what? The type of lube would significantly change the friction coefficient.

 

[RaceDiagnostics]

No lube specified but they did come out oily and I didn't dry them off before reusing.

 

[RaceDiagnostics]

I rebuilt the heads today but came across a new problem.

You will see that 3 of the cam towers are missing. I was able to buy replacement for these from ebay, same part number stamped on them as the old parts but it turns out that what was supplied are 0.1mm undersize. Old ones are 49.4mm diameter, the replacements are 49.3mm.

So I have two options, get the three journals ground down by 0.1mm (that would be good to get rid of the scring on the cam journals), or reuse the old worn bearings. One issue I see with getting the cam journals ground down is, will the engine shop be able to keep concentric with the other journals?

 

[Melvyn Best]

I suspect the bearing carriers would need to be bolted to the heads and line bored ?

 

[RaceDiagnostics]

The repair manual calls for cam shaft grinding rather than line boring the bearings. But of course it expects all the journals to be ground.

I don't really want to change the bearing to fit the cam as the cam journals are scored so would soon have the same issue on the new bearings.

The full set of undersize bearings are also NLA. So that's not an option.

Just trying to work out the best way forward with bad options.

Are you saying that the machine shop will not be able to grind just one journal and keep concentricity?

If that's the case I'll just have to go with the old bearings.

PS new cams and bearing would be best part of £3k so not an option

 

[8ob]

Melvyn is right, they will need boring. I don't know whether Mercedes do this but most of the cam bearings on motors I have worked on get progressively smaller towards the back of the engine. If this is the case with the merc engine the replacement bearing housings may have already been machined for placement elsewhere in the line-up. Its the same for big end bearing caps, they may all share the same part number but they belong to one con rod once they have been machined.

Bob

 

[RaceDiagnostics]

No, small at the front, mid in the next two and large on the rear two. The rearmost has special oil ways in it. The pic is of two of the "special" rears.

The rear ones have a different part number to all the others.

I've emailed a couple of engineerings shops to ask if they can do it, two I called today were closed due to covid.

 

[Melvyn Best]

We used to have a very good engine machine shop in Cambridge that would have reground the camshaft bearings , bored the bearing carriers, fitted new bearings to the carriers and then line bored to side. They did a few Volvo heads for me back in the 80s when the camshaft oil feed in the head had become blocked with carbon , so the job can be done

 

[RaceDiagnostics]

Got one reply so far saying no problem but shut for covid, fortunately its not urgent.

 

[OJCar]

I would think that a competent cam grinder is going to have no problem keeping in grinding the bearing surface concentric with the rest of the cam shaft
as it is a circular bearing surface concentric to the shaft to start with.

There are some machinists in the main forum who will know, try asking there is a separate thread, they may not be reading this thread.

 

[RaceDiagnostics]

Not much progress today, life outside the garage interfered.

Lower chain guide rails.

New front crank seal.

Tapped into place.

Finding TDC.

Lining up the distributer sprocket, I'm not sure why it needs to be lined up.

Back of the crank seal filled with grease to stop the spring popping out when mounting. Rubber grease holding in the O rings. Oil pump chain guide fitted. Now there was no gasket on the timing cover when I took it off but the manual calls for a sealant to be applied when replacing.

I have this Permatex gasket maker or can pick up some Loctite 5980 from Halfords, any thoughts?

New idler sprocket.

 

[jpmillermatic]

I have used both....as long as the directions are followed to a T.....you should have no problem.

Personally, I like to apply a bead of material from a tube. I think the permatex you have is on a brush?

JP