Stubborn Nut

[Mark Gordon]

I'm in the final stages of tearing down my 4.2 L engine for a rebuild. The only thing stopping me now is the nut that holds the drive gear onto the bottom of the distributor drive shaft. It wont budge. I have tried heating it with a propane torch, soaking with penetrating oil (both Liquid Wrench and ATF/acetone), judicious tapping with a cold chisel and forcing it as hard as I can with a socket wrench. Still no luck. I am concerned about breaking either the drive gear or the helical gear on the crankshaft. I have considered using a carborundum disc on a Dremel tool to cut it off. Has anyone experienced this problem or have ideas for me?

[ChrisC]

I found that a propane torch was usually not hot enough to get frozen nuts to release. When I subsequently gave said frozen nuts to my Jaguar specialist they used oxyacetylene which made the nut hot very quickly in a local area.

It may well be that a local garage can do the same for you in the absence of any better ideas from other more knowledgeable folk...

[christopher storey]

I hate to say this Mark, but are you sure it is not a left hand thread ? The direction of rotation seen from the bottom is clockwise, which suggests that it is either locked ( and I cannot remember if it is ) or left hand thread

PS Mark : I have just looked up the parts list which shows the nut as UFN256/L and I feel sure the L indicates left hand thread

[Mark Gordon]

There was a lock tab on the nut which I tapped down, so it's not holding me up at all. Pete C. checked one of the nuts that he had in his shop and confirmed that it is the normal right hand thread. That thought occurred to me early on and I tried to turn the nut clockwise to no avail. I just borrowed a 7/8" six point socket and a 24" breaker bar from a friend. I'm going to have a go with them and will report back.

[Mark Gordon]

Success! All that was lacking was the 24" breaker bar and enough courage to put some force to it. I must say that that was one tight nut. I didn't measure the removal torque, but it took more than what was needed to remove the crankshaft cap bolts which are torqued to 83 lb ft. I was afraid that I was going to break one or both of the gears, but no damage. Thanks for your advice, Christopher and Chris. Next step will be to arrange for the machine shop work. I hope that I'm not being optimistic with a completion date of March-April.

[christopher storey]

Mark : I've just referred to my fastener guide, and L is not for left hand but means the nut is a steel one . You should be able to see what thread it is anyway if there are any threads protruding . To avoid straining the shaft helical gears , some people advocate holding the other end of the shaft in an upturned 3/8 socket ( i.e in the drive end) with a hex allen key in the operative end of the socket . It can't do any harm to restrain it that way

Edit : Ah just seen that you've got it off. thank goodness for that!

[PeterCrespin]

I'm thinking of using this thread title as my new Avatar....

Here's hoping you get away with just the crank clean-out, rebore and some valve seat work Mark. Can you take some pics of the worst exhaust valve please? My iPhone shots came out a bit fuzzy.

One thing's for certain, your engine is going to feel stronger when you've finished, based on what has been found, and yet will not require top-to-tail machining, as some aspects are still in spec. This is going to be a great value-for-money rebuild and far more satisfying than giving it to someone else.

[1954Etype]

Mark, Pete briefly mentioned cleaning out the crank. It is vital that the hex sludge plugs are removed and the crank thoroughly cleaned internally before building the engine up - you wouldn't believe the amount of crud that come out! Failure to do so will take out your journals and shells after a few revs!

[Mark Gordon]

Angus,
I have spoken with Larry at the machine shop. He plans on: removing the crank plugs, hot tank cleaning of the block, head, cam covers and sump, cleaning the oil galleries and magnafluxing the crank, measuring the journals then regrinding or polishing the crank as needed, refacing the flywheel, balancing the crank, clutch and flywheel as a unit, skimming the head, grinding the valve seats and adjusting the valves. Pete checked the head components and told me that the valve guides, seats and valves are all reusable. I measured the rod journals and they all measured 2.055" to 2.089"; spec. calls for 2.086". I've known Larry for about 15 years and am confident that he knows what he is doing and will not do extra stuff just to pad the bill and with Pete and those of you on the forum, I feel confident that when she's all back together, I will have an engine and car that I can drive as it was intended. As always, I am very grateful for everyone's expertise and advice. Pete, I will take photos of all of the valves and email them to you this evening.

[PeterCrespin]

I measured the rod journals and they all measured 2.055" to 2.089"; spec. calls for 2.086".

Was that a typo Mark? I thought you said all in spec, so I assume 2.085" not thirty thou under 2.055"?

[1954Etype]

Angus,
I have spoken with Larry at the machine shop. He plans on: removing the crank plugs, hot tank cleaning of the block, head, cam covers and sump, cleaning the oil galleries and magnafluxing the crank, measuring the journals then regrinding or polishing the crank as needed, refacing the flywheel, balancing the crank, clutch and flywheel as a unit, skimming the head, grinding the valve seats and adjusting the valves. Pete checked the head components and told me that the valve guides, seats and valves are all reusable. I measured the rod journals and they all measured 2.055" to 2.089"; spec. calls for 2.086". I've known Larry for about 15 years and am confident that he knows what he is doing and will not do extra stuff just to pad the bill and with Pete and those of you on the forum, I feel confident that when she's all back together, I will have an engine and car that I can drive as it was intended. As always, I am very grateful for everyone's expertise and advice. Pete, I will take photos of all of the valves and email them to you this evening.

Sounds good Mark - if I was going to be uber picky, I'd get him to confirm that he will clean the crank journals after any regrinding.

[Mark Gordon]

I'm at work and have the measurements at home, but as I recall, one of the journals did read 2.055" I will recheck this evening.

[Mark Gordon]

Was that a typo Mark? I thought you said all in spec, so I assume 2.085" not thirty thou under 2.055"?

I'm at work and have the measurements at home, but as I recall, one of the journals did read 2.055" I will recheck this evening.

[Mark Gordon]

Pete,

I checked my recorded measurements and it wasn't really a typo, it was more a case of CRS (Can't Remember ...Stuff). The measurements for the rod journals were: #1=2.0885, #2=2.086, #3=2.0855, #4=2.089, #5=2.087, #6=2.0855. Not too bad for an engine that has almost 180,000 miles on it? Do you think I can get by with just a polishing of the crank, i.e. no regrinding?

[PeterCrespin]

The measurements for the rod journals were: #1=2.0885, #2=2.086, #3=2.0855, #4=2.089, #5=2.087, #6=2.0855. Not too bad for an engine that has almost 180,000 miles on it? Do you think I can get by with just a polishing of the crank, i.e. no regrinding?

Your machinist will measure in multiple spots to check for ovality and parallel. I will be surprised if he comes up with journals that are two and a half and three thou oversize. Half a thou under is fine assuming it is consistent axially and radially. Three thou over requires a regrind in itself down to spec, so unless the crank had been built up and reground (badly) it is probably a measuring anomaly. Three thou would be too much to polish also. He's an experienced machinist so you'll get good advice I'm sure.

I expect you'll be fitting standard shells again but wait and see.

Pete

,

[Mark Gordon]

"measuring anomoly." That's a polite way of saying "you screwed up the measurements," isn't it?