A few years ago my 87 V-12 had a head gasket failure. Car ran fine. I parked for a few minutes and when I attempted to start the car, the 3B cylinder was full of coolant. The engine started, but hydraulic lock split the liner. I shut the engine off.
I pulled the left head and found the damage. I bought a used engine to install in the car and this one sat in the corner of the garage for the last five years. I decided to rebuild it. Main bearings and rod bearings were std. I did a teardown, replaced the cracked liner, honed all twelve. Crank was installed with new bearings and rotated fine.
New rings and standard bearings for the rods were installed. Even having wiped the liners with oil after the honing and using assembly lube on all bearings there seemed to be a lot of friction, but the crank still turned. The rod and piston for 3B was replaced during the disassembly and cleaning in case it was bent.
Now with heads installed, new timing chain and tensioner, I can’t get the engine to turn over to finish checking the valves without a half inch drive breaker bar and a four foot long pipe on the handle. This raises a red flag!
I expect some friction and resistance, but this much? I think I will start with the rod bearings and see what happens if I loosen the rod bolts, which would point to the rod bearings.
I did see a clip of the same sort of problem on a V8 , the rear main rope oil seal was fitted wrong , and it was binding , worth a look if it has rope seal
Then if the crank was free with bearings and seals , must be something else , always worth turning a engine by hand after fitting each part , hmm !!
Yes. I agree with “residentalien”… My crank was nice and free until I fitted the rope seal…then I couldn’t spin it. This before adding the rods and pistons.
Rope seal is a bit fiddly and needs to be well “seated” in the bearing housings.
I could spin my engine with everything attached with a standard spanner and a bit of effort.
Can you just loosen off the rope seal cap and see if it spins easier??
Matt
Yes, I do recall messing with rope seals in other critters. In those, seating and trimming was almost an art form. And a bit counterintuitievely, well oiled to ease the friction and starting. And to prevent a glaze and thusly, a leaker, forever more…
I pulled the rear crank bearing housing to examine the rope seal as suggested. With the rear bearing housing removed, the engine was still bound up. So, I started loosening one cap at a time, and then the camshaft bearings, With everything loose the engine turned over fine.
The torque wrench that I used has both foot pound and newton meter scales. I torqued everything at the same time but read the wrong scale. Instead of torqueing everything to the correct newton meter value I had torqued everything to foot pounds.
After retorquing everything to the correct value, this time in newton meters, the engine turns as it should.
The lesson is to make sure that you are using the correct torque values.
It’s good news that you sorted the problem but l can’t quite get my head around how overtorquing the fasteners a bit would cause bearing caps and big end caps to lock up.
Even at low torque the caps would be fully seated and any further turning would just increase the load on the fastener rather than close up the clearances.
Or am l missing something. (quite possible)
I am open to explanations. The rear bearing cap with the rope seal was removed, but the bind was still there until everything was loosened.
I do not understand why it was bound and why it now turns over either. The only variable was that foot pound torque was about 25% more. I used a click type wrench for the 1/2" stud nuts and a bar type with two scales for the smaller cap nuts, rods and cam shaft bearings.
Having spent a majority of my life owning/operating a contract machining company, I can tell you that the metal will in fact continue to deform as additional torque is applied. The caps would start to swell in all directions away from the centerline of the bolts. It would not take much to cause binding, especially when there are many caps all tightening up. It would be easy to prove with a dial indicator and magnetic base.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
12
Having spent a majority of my life owning/operating a contract
machining company, I can tell you that the metal will in fact continue
to deform as additional torque is applied.
IIRC, the proper way to machine an engine block involves a plate that
simulates a head, with head nuts or bolts torqued to spec. It’s the only way
the machining of the bores will come out right.
That said, for overtorqued bolts to cause the engine to seize up would seem
to involve some really tight clearances.
AKA “TORQUE PLATE”. Used when boring the cylinders to a standard over size, to correct irregular wear. Boring bar yo move most of the material. A precision wet hone for the last cut. and to produce the proper :cross hatch: pattern to enable the rigs to seat. Firmly seating the engine block and careful alignment to the crank center to assure that the “holes” are properly placed.
O’wise “wonky” movement of the crank results. Aka “tight spots”
as one turns the crank.
Bill Terry told me many years ago that once he made and starting using a torque part the engine problem on his race cars were reduced.
Bob
889076
Plymouth, Mi.
