924Board.org

[PanamaCarrera]

I am refitting my crankshaft

I have installed the bearings, lightly oiled, and tightened the bearing caps to 80nM.

Now, I cannot rotate the crankshaft, neither by hand or with a few whacks with a wooden block to some of the bearing weights.

Is that normal?

Thanks

Nigel
_________________
Nigel Walker

[Raceboy]

Definitely not normal. Were the bearings oversize by any chance?
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[PanamaCarrera]

Nope, putting the motor together with the same bearings as came off the car...

Shop did not record which bearing shell came off which bearing, could this be a problem?

Have the thrust bearing shell on number three.

N
_________________
Nigel Walker

[morghen]

[WEASEL149]

I would disassemble everything first.

Make sure everything is absolutely surgically clean with solvent such as brake cleaner.

The backs of the shells have to be spotless and dry, as well as the surface they mate to in the block and bearing cap.

Also make absolutely sure the mating surface around the locating dowels and on each cap is clean and dry.

The best thing to do then would be to reassemble with some plastigauge on the journals to check clearances. The journals need to be dry and not lubed when you do this. Do not turn the crank when you've torqued it back up.

After this you disassemble again and measure the plastigauge using the included scale. I can't remember clearances off the top of my head but they should be ideally 0.002"-0.003".

If some are just slightly tight and others slightly loose you can try swapping them between journals and you may then find the original order.

If you're unsure of anything though, find a good engine shop and get them to check the journals sizes and bearing clearances with proper measuring equipment.

Remember it's important that the backs of the shells and corresponding mating surface are clean and dry NOT lubricated.
Only the insides of the shells and the journal they mate to should be oiled otherwise the crank may feel tight.
_________________
1979 UK 932

[Paul]

+1 but I would buy and install new bearings.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[Fifty50Plus]

Possibly mixed up main caps or on backwards......
_________________
1979 924 NA race car H-Prod SCCA
1982 924 NA race car - Sold
1981 924 Turbo sold
1982 924 Turbo sold
1972 911 E race car - traded for Cayenne Diesel
1975 914 1.8 Building for H-Prod SCCA

[PanamaCarrera]

Thanks guys, really useful feedback.

Lots to do next week-end when I have time to get on with the car again.

Will let you all know how I progress.

Thanks again.

N
_________________
Nigel Walker

[WEASEL149]

[PanamaCarrera]

Nope, caps on the right way, and right number sequence....

Praise be Porsche put numbers on them - everything else the shop touched they just jumbled up and gave back to me in a box!

I had talked to them about doing a full rebuild so probably my fault but I just don't have time to wait for new parts at the moment - car has to be ready to go into storage in one piece by the end of August.

Cheers!

N
_________________
Nigel Walker

[Fifty50Plus]

Okay, time for root cause analysis. Untorque one main cap at a time and try turning the crank. It's pretty important to the future of your engine that you find why it locked up. If it's mismatched bearing shells that caused the problem, measure each main journal carefully for size before you install new bearings.
BOL
_________________
1979 924 NA race car H-Prod SCCA
1982 924 NA race car - Sold
1981 924 Turbo sold
1982 924 Turbo sold
1972 911 E race car - traded for Cayenne Diesel
1975 914 1.8 Building for H-Prod SCCA

[juha_teuvonnen]

Something is very wrong. I would measure all parts involved and determine the source of the problem before putting the engine back together. You should be able to turn crank by hand, otherwise the engine will self-destruct on startup.

[PanamaCarrera]

Hi Folks

I've had a really good day working on the car.

Following your collective advice I started off dismantling everything and giving all the parts a good clean.

Next I installed the thrust bearing, making sure the flanges with the worn faces were facing toward the back of the engine.

I then installed the regular bearing shells one journal behind the positions they had last week, 1-2, 2-4, 4-5, 5-1.

Next to put the bearing caps in place and hand tight - the crank turned.

Then, in increments of 10Nm at a time I tightened the bolts, checking if I could turn the crank at each level.

I must admit tightening the final bolts at 80Nm and checking if the crank would turn was a bit like waiting for the last ball on lottery night - but it came up a winner with the crank turning easily.

Then on to the pistons. Cleaning the encrusted carbon deposit off the first piston I found a #2 stamped into the crown, and on cleaning the other three I found numbers 1, 3 and 4 - so I do know the piston positions - I'm not sure if the standard pistons are numbered but thankfully the Kolbenschmidt pistons on my car were numbered at the factory.

So, all's well that ends well, as someone once said. As I sit here tonight with a beer and a burger at hand the major internals are in place. Tomorrow on with the oil pan and I can start reassembling the head.

Thanks guys for all you advice, really helped me out of the dwang.

Cheers!

N
_________________
Nigel Walker

[Raceboy]

Congrats on the success, glad it worked out without any further issues.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche