question Advice required

 

 

 

take it back out real seal aint going to make that much difference/ but if that is not what you want to hear give it a tow start and give it a blast around and see if it frees of

Edited February 1, 2015 by cosrec

I agree, the rear main seal would have a negligible effect as a reason for a tight crank.

I, too have towed jeeps around with the engine turning to free them off a little after

the installation of new bearings. If it's really tight try helping it a little by removing the plugs.

I assume that the rods are all true and that you've not gone the extra yard when tightening

the end caps? A complete last resort would be to drop the pan and ever so slightly back off

the end caps, replace the pan and oil etc and run the engine for five minutes or so, then repeat

the process to torque specs. Just about everybody will tell you not to do this but I have, with

complete success and no apparent repercussions.

I agree, the rear main seal would have a negligible effect as a reason for a tight crank.

I, too have towed jeeps around with the engine turning to free them off a little after

the installation of new bearings. If it's really tight try helping it a little by removing the plugs.

I assume that the rods are all true and that you've not gone the extra yard when tightening

the end caps? A complete last resort would be to drop the pan and ever so slightly back off

the end caps, replace the pan and oil etc and run the engine for five minutes or so, then repeat

the process to torque specs. Just about everybody will tell you not to do this but I have, with

complete success and no apparent repercussions.

man of my own heart but if you are not sure of what you have done take it it back out and start again unless you are completely confident with your workmanship then go for it Edited February 2, 2015 by cosrec

The mere fact you posted it seemed tight hinted all was not good so why go further sort it which way you want

I agree, the rear main seal would have a negligible effect as a reason for a tight crank.

I, too have towed jeeps around with the engine turning to free them off a little after

the installation of new bearings. If it's really tight try helping it a little by removing the plugs.

I assume that the rods are all true and that you've not gone the extra yard when tightening

the end caps? A complete last resort would be to drop the pan and ever so slightly back off

the end caps, replace the pan and oil etc and run the engine for five minutes or so, then repeat

the process to torque specs. Just about everybody will tell you not to do this but I have, with

complete success and no apparent repercussions.

like try it

A few points to ponder perhaps, you say you replaced the mains and big ends with the same size bearings as you took out because the journals were good;

 

1 did you check for ovality of the journals ? it is unusual to need to change all bearings and not require some degree of turning on the journal surfaces.

 

2 what torque did you use on the the caps and rods, did you take them down in three stages equally?

 

3 Did you replace the front cam shaft bearing ?

 

4 did you check the crank free play when the mains were fully torqued and what torque have you put on the bottom pulley nut

 

5 If the neoprene rear seal is that tight it will burn out very quickly and score the crank in the process

 

6 There is nothing wrong with rope seals as long as they are the correct diameter, fitted correctly and the ends are cut absolutely square ( I always add a dab of silicone sealant to the ends before placing the cap on.

 

7 I would not recommend slackening of the bearing caps, you can and will induce stress in the components, if you need to do this to get free movement it is indicative of ovality in either the crank or the rods/caps or both.

 

8 what were your journal and big end measurements at strip down ?

 

Pete

Rear seal is problem, I would bet on it. There was a particular gasket set that had a seal in it that was too tight, I had this problem. I got a replacement from another source and was fine (none of these were rope seals). Years later I came across a lot of information by chance on G503 forum and many have been caught out. The heat build up from the tight seal has cause failure of the rear main bearing in some cases.

Go to G503 and search for rear main seals, you will be reading it for hours!

 

regards, Richard

Hi,

 

Those who say a seal cannot cause this are, with the greatest respect, wrong. We had exactly this problem with a new neoprene rear seal. We proved it on the bench and confirmed that was the cause. The starter would only turn the engine very slowly. We tow started the Jeep and drove it around and it freed up. It would then start fine on the starter. We didn't know about the potential for overheating the rear main but the vehicle has done many miles since the build, including at least one trip to France so I'm confident it's ok.

 

You need to be certain it's the seal though, and it's at your risk .

 

- MG

Edited February 2, 2015 by TooTallMike

Thanks all - will update soon, but am betting it is seal as everything was fine and turning though a bit tight not excessivley though. All tightened and gradually torqued etc with a standard set of shells replacing older ones, the old ones were scored but not excessivley just thought I would replace them when I was refurbishing everything else.

 

 

Gary

Did you install the seal in the proper location? I will admit that I installed a rope seal in the 'forward' channel (not the rear one) and that it seized the crank requiring a polish to correct the journal. The first grove is an oil return grove (there is a hole in the cap, the second, or REAR grove is where the seal goes.

 

Here is a photo of the neoprene seal.. if you look just forward (to the left) you will see the oil return grove. make sure that you did not put the seal in there.

 

 

I recall the 'seal issue' being more about not sealing that about being tight from the G503 site. Its more likely that the seal is right, just installed in the wrong place. It will fit in both groves.

There was definitely a long thread on G503 regarding tight seals.

 

John

I'm sure just about every possible incarnation of every possible topic has been discussed on the G503 forum.

 

I recall that there was a vitron lip issue traced back to (IIRC) a Federal Mogoul part? its been a while. I used rope seals every time.. so I didn't follow it closely.

Another thing worth considering is the condition of the battery leads. I did a similar job years ago. Before I had the engine out the engine turned over pretty well, however with new rings, shells and seals it turned over to slowly.

A friend suggested that it could be the battery leads as he had experienced the same problem on an escort van. I admit I was dubious as the Jeep had thick 6V leads and I was running with 12V. I replaced them with new 12V cables and the engine flew over and fired up. When I stripped the old leads it was clear that they had deteriorated over the years building up a massive resistance, which only came to light with the tighter engine.

 

If you are running 6V the correct size cables can be made from 70mm welding cable and correct crimp lugs, incidentally it helps to fit an extra earth lead from the battery tray to the steady bracket at the back of the starter motor.

 

John

12V cables have twice the resistance and half the amp rating of 6V cables.

 

You had bad 6V cables, but running 12V cables (again, twice the resistance and half the amp capacity) is not going to to be a long term solution.

 

Easiest way to rule out a starter issue is to take the spark plugs out and crank it over. If the motor turns over quicker then you have a starter/ground issue. If it stays the same you most likely have to open it back up and start double checking things.

 

Did you palstigauge the bearings during assembly? That has to be the most common thing people forget to do... they assume that the new parts will magically 'fit' and 'work' but you need .0015 to .003 clearance on bearings. Most people shoot for .001 to allow for wear and make good oil pressure.. but .002 is still OK. .003 is the limit on new bearings. Over that you need to have the journals mic'd and possible ground to the next under size.

I think you have answered your own question if the old seals were scored the you will have

high spots on the crank which will run on the new bearings

C

If you put new bearing shells in the same size as the originals without regrinding the crank, the bearings will not be any tighter than the old ones, the journal diameter cannot have "grown".

 

If you were able to turn the engine over as you reassembled it, I would check the battery leads as suggested earlier.