Jump to content

'40 Zephyr - won't start when hot


nasmith
 Share

Recommended Posts

Well, I don't know where to begin - and I don't to make this too lengthy. I need help from all of you Zephyr wizards. My '40 LZ starts quickly when cold and runs great. When hot, or even warm, it behaves like it has a dead battery when trying to start it. I have overhauled the engine - rebored .030 over, new pistons, rings and wrist pins, new cam bearings, valves ground and lapped, valve lifters adjusted (adjustable solid lifters), new timing gears, new oil pump drive gears, rebuilt carb and fuel pump and distributor set up by Jake. The rod and main bearings are within tolerance so they were not changed. In an attempt to fix the obvious, a rebuilt starter was installed, new cables were provided, and the starter solenoid was replaced. The battery is a recent replacement and is fully charged and when a substitute battery was used, it didn't improve the situation. When hot, the engine cranks normally with the spark plugs removed - ignition on or off. When hot the engine cranks like it has a dead battery with the spark plugs installed - ignition on or off. All grounds have been checked and cleaned - my multimeter shows continuity for all electrical connections. I have searchrd the archives and have done an incredible amount of troubleshooting and am really looking for help from all of you experts. Norm

Link to comment
Share on other sites

Well Norm, logic says that a problem like you describe has got to be the pistons. They are the only thing in the engine that expands much. I think rebuilders who know the V-12's propensity to burn oil, err to the tight side when setting up the pistons in the bores. It could be a good thing if your engine will finally break in, and shed the tight spots, It might result in a long lasting, good running engine. Personally, I would drive it several 100 miles, and leave it running until you return home, park it, try to start it, if it still won't, let it cool, and drive it some more, an additive in the oil might be wise too, to reduce the friction in the bores, it should loosen up in time, and run just fine, hopefully

Link to comment
Share on other sites

Rolf - thanks for the reply. That had crossed my mind, but I thought the slow cranking would continue, even with the plugs removed. The slow cranking, when hot, is somewhat irregular; that is, it speeds up and slows down to a stop in fits and starts, if you know what I mean. The re-bore was done for a .0025 to .003 clearance and the pistons are aluminum from Egge. What additive would you suggest? I have put MMO in it, but it doesn't seem to help and I have been driving it in hopes that it would loosen up. I suppose it's my imagination, but it seems like it is getting worse, rather than better.

Norm

Link to comment
Share on other sites

Norm, Unless I am missing something large here, and the engine still turns over slowly with the plugs out, then the problem is in the battery, cables, or starter, as the time required to pull all 12 plugs would allow it to cool down a lot, it might be interesting to take a compression check while you have the plugs out, compression from 100 to 125 PSI could cause it to turn a lot more slowly too, as far as slippery oils or additives, I do not have much experience, so I would just try to get a solid hunch from reading the blurbs on the cans at the parts house, I have used rislone in the past, but not much else, but whatever you try, put it in through the removed spark plug hole, and see if the starter turns faster and less irregularly. Also Egge should have the number for the expansion rate of the pistons, and who set the end gap on the rings, and how much is it?? Other than that, I will have to defer to greater minds than mine, it is a strange one alright

Link to comment
Share on other sites

Rolf, actually what I meant was that the engine turns over normally when the plugs are out but returns to slow cranking, while still "warm", when they are replaced. This seemed to me to indicate that there was not any sort of mechanical resistance to deal with. When the engine was first installed, with very few miles on it, the compressions were 105 - 110. I will check it again.

Link to comment
Share on other sites

Could even be something as simple as a bad ground. The added load of the compression is just enough to cause this slow cranking. The ground connection to the cylinder head may be at fault especially if you have a fresh coat of paint where it attaches. Did you paint the flange where the starter motor bolts to the pan? Sounds silly but 6 volts with high current needs a good ground.

If your engine is not over heating I suspect the end gaps on the rings are probably ok. checking the end gaps on all the rings is sometimes over looked. The standard is .003" per inch of bore.

Link to comment
Share on other sites

Some thing wrong with this picture, I thnk you said

you have mehanical lifter's. my question is was the

Cam re-ground for the mechanical lifters if not you

may have to put your hydraulic lifters back in.

Z man

Link to comment
Share on other sites

Thanks for the input. Peecher, I have checked the grounding and cleaned or polished the contact points. When checked with a multi meter there is apparently no electrical resistance. The rings were gapped at the bottom of the piston travel at .010. Zman, the mechanical lifters were installed by a previous owner and the cam was regound for use with mechanical lifters. Rolf, in response to your earlier comment, the compression has been rechecked and is from 105 to 115 so I guess that could contribute to the problem. Your comments and suggestions are all really appreciated and I am checking or confirming each one. When I re-assembled the engine I installed the little bracket at the forward end of the starter (it didn't have one when I got the car). I am going to remove it to see if it is putting any kind of a bind on the starter drive.

Link to comment
Share on other sites

That may be a good idea Norm, but the fact is the starter turns normally when thr engine is cold, and only slows when it is hot, I vote that it needs more break in time, and after 1000 miles or so it will be starting hot fine, I hope anyway

Link to comment
Share on other sites

Guest imported_V12Bill

I agree with Rolf and Dee. I do disagree with Rolf about adding an additive to the oil though. If you have high spots to wear off you will take a lot longer to wear off the high spots with an additive in the oil. Remember the additives make the oil more slippery. You stated that Jake had reset your distributor. Did you have Jake rebuild your coil also? I have a 48 that had a rebuilt coil (not by Jake) that was bad. It behaved exactly like your 41 is doing including slow cranking when hot. Finally I put a Jake rebuilt coil in the car and all my problems went away. It seems you have tried everything else why not a new coil?

Link to comment
Share on other sites

That is an excellent point Bill, I was thinking a squirt of slippery down the bores that resulted in faster turning would prove the "too tight" theory, and not really make the oil different, in the old days guys used to pour Bon-Ami down the carburetor while the engine was running, to hasten seating of the rings and break in, I have no personal knowledge this ever worked, and there was something called "break-in oil" that I never used either, but products of this nature seem like they would be in the right ball-park??? But then maybe not?? Mysteries abound-

Link to comment
Share on other sites

I hate beating on a dead horse, but are you **SURE** that your battery is strong enough to crank a hot engine? I've had that "hot start" problem with other cars and installing a heavy duty battery has always fixed it.

Also, be sure that you are **NOT** using 12 volt battery cables, they just can't handle the current required to crank that V-12 engine. All Lincoln V-12s seem to crank slowly when hot. I was having a slow cranking problem with my '39 Zephyr and I replaced a "good" battery with one like the one in my '41 Continental (attachment, an Interstate type 2 with 750 cranking amps) and the engine now starts more quickly - still a little reluctant on the first spin, but much better than before.

You might put a voltmeter on the starter to see just how much voltage is present while cranking. If it's substantially less than 6 volts, there's resistance somewhere in the circut.

post-32768-143137941117_thumb.jpg

Link to comment
Share on other sites

Thanks for the excellent suggestions you guys. I've had guests for the last couple of days, so not much attention has been given to the LZ. I have pulled the new (rebuilt) starter and had it checked. It checks out fine. I have been checking circuits, grounds and cabling with a very old set of jumpers; I now realize some errors have been made because of their poor condition. As an example, I tried to run the starter with 12 volts and it wouldn't turn over so I will toss the old jumpers and get new ones. Again tried cranking with the plugs out and it cranks furiously.

While the plugs were out, I shot one squirt of MMO into each cylinder and cranked it again with the plugs out; again it cranked furiously. Put the plugs in and while still cold, tried cranking again. Well, it acted just like when hot - almost no cranking - very slow and way too slow to start. I guess this says my starting system is too weak to overcome the new higher compression (105 - 115). I have considered the coil, but when it runs, I get a really strong spark. I need help to understand how the coil can affect the cranking speed, especially when cranking with the ignition off. The battery is an Exide Heavy Duty with a 750 CA rating. I will put the starter back in tomorrow and leave the pan bolt brace off and see where we go from there. Thanks again for all of your help - this is truly a great resource.

Norm

Link to comment
Share on other sites

Guest imported_V12Bill

Don't remove the pan bolt brace. It prevents the end of the starter from moving about and binding up the starter bendix.

Link to comment
Share on other sites

Thanks Bill; I wanted to see if the brace was causing binding due to mis-alignment. The car didn't have one when I got it so a new brace (repop - how accurate are they?) was installed when I put the engine together after the rebuild.

Norm

Link to comment
Share on other sites

Norm, I have recently rebuilt a couple of these 12's and noticed that the rings sets for each had different "tension". The Grant rings used were noticeably stronger when compressed compared to the original Ford type used on the second engine. When assembled there is noticeably more drag on the engine with the Grant rings. The combination of this increased drag and restored compression may be a major contributing factor to the slow cranking? The condition of the starting system cables is really important. Checking with an ohm meter just isn't good enough. Some kind of "load" testing on the cables probably should be done.

After sorting out this aspect you may want to use a break in additive to reduce some of this initial friction. GM has a product called E.O.S. ( p/n 1052367) which is rich in zinc and phostates and should help your 12 get broken in.

Link to comment
Share on other sites

I have the same problem with my 47 Lincoln Club Coupe after engine rebuilding. The engine has to cool (along with the driver) for about 10 minutes befroe it will turn over enough to start. I assumed it is due to break in not long enough or to the starter being less effective when it is warm. I have Lucas oil additive in it, on the advice of the rebuild shop, but don't know how it compares to EOS from GM. I am hoping the problem resolves when the engine is driven further.

Link to comment
Share on other sites

I did a couple of things today and the LZ seems to start with ease now. It is late now and the car will be tested some more tomorrow to confirm the results; I will share what was done, and the outcome, tomorrow afternoon. Again, thanks a million for all of the ideas and suggestions.

Norm

Link to comment
Share on other sites

Well, I have driven the LZ "here and there" today and it has started every time. Yesterday, I put the starter back in and did not connect the brace to the pan bolt. The brace did not seem to line up very well and it would not fit if either bolt was tightened before the other was installed. Both bolts could be started loosly and then tightened. It seemed like the starter was being pulled into misalignment as the tightening was done; not much, mind you, but I would guess several thousandths. The car cranks with vigor when cold but is still erratic when warm - but it cranks well enough to start. I suspect the misalignment created some binding, that when added to the resistance due higher compression, made it crank so slow there was no start. In time it should, as Rolf suggests, loosen up enough to be consistent.

One other theory tested today was the possibility that the flywheel is rubbing on the oil pump idler cover bolts inside the bell housing. When I tore down the engine the idler cover was secured with bolts and lock washers; when the engine was re-assembled, it was put back together as I found it. When the flywheel was installed, it was rubbing on one of the idler cover bolts; I found another bolt with a thinner head and fixed the rubbing flywheel. After installation of the engine, I discovered that the proper idler cover installation calls for safety wiring the bolts instead of using lock washers. Yesterday while the starter was out, I could see the face of the flywheel and there were no marks showing evidence of interference. I did smear some lubriplate on the flywheel.

I am convinced that the brace was the problem; however, time will tell. Thanks to all of you, this has been a experience to prove the value of this forum.

Norm

Link to comment
Share on other sites

Norm, You might want to check the starter armature for straightness. If it's bent even a little it will be magnified out where the drive Bendix is attached and cause binding with the flywheel. This condition can actualy cause the starter motor to wobble. The brace will try to hold it in place and cause binding so this may explain the "mis-alignment". I came across this problem with one of my starters. The whole idea of the brace is to keep the starter motor from exerting sideway pressure on the motor when it engages the flywheel.

Link to comment
Share on other sites

Thanks Dee. The starter is a rebuilt, so I "assume" (we know about that word, don't we?) that the armature and shaft were checked for run out. When I had the rebuilt starter out the other day, I had it checked in an electrical shop that specializes in starters and they said it was ok - another opportunity to "assume". Interestingly, the Chassis Parts Catalogue does not call for the brace ("bracket" in the catalog) when the 7RA-11002 starter is used which is the one most likely in my car. I think I may enlarge the holes in the bracket so when it is tightened, it does not change the mounting angle.

Norm

Link to comment
Share on other sites

norm from rudy same car same problem have tried everthing you have tried same results my next step is again check the timing on my rebuilt distributor. my engine was renently rebuilt. everthing except the pistons; however new rings. i8 have ran the engine a total of 40 hours in the shop. i did this in case the tolerences were to tight. same results. im at acomplete loss.have you had further luck. rudy

Link to comment
Share on other sites

Hi Rudy - My problem was really due to very slow and sometimes erratic cranking. In my opinion, the problem was a misaligned starter causing the Bendix drive to bind when it engaged the flywheel. The bracket at the forward end of the starter was apparently holding the starter at a slight angle. When the bracket was removed, the engine cranked vigorously when cold but still had some symptoms (ie: slower and slightly erratic cranking) that you would expect of a tight, overhauled engine; however, it now cranks well enough for a start. I expect it to crank better and better as some miles are put on the engine. My engine starts easily if I can get it to crank normally. A rolling down hill start will fire it up instantaneously. Is your problem slow cranking or is it hard to start with normal cranking?

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...