Morris Minor Owners Club

I have recently rebuilt my 1098 engine and have been fastidious in making sure that everything has been checked and measured before re assembly.
The crank rotates beautifully with new bearings.
I have measured the bores , pistons etc and all is good.
The problem I have is that when I fit the pistons in the bores with the new rings the engine is tight to turn over.
I have correctly gapped all the new rings in the bores and have checked that there is sufficient radial depth in the ring slots. It seems to me that there is quite a lot of tension in the new rings and they are gripping the bores tightly. I suspect that the 3 part oil control rings are the tightest.
The engine turned freely with the original rings on the pistons.
The new rings are from esm and are of American origin.
The engine will turn on the starter motor with the plugs out but will not turn when compression is added.
Has anybody else come across this problem?

I've just done the same job the only difference being I used rings from Mini Spares. The new rings did give more resistance than the old ones but I didn't have the same issue as you with the plugs in. It could possibly be a failing battery or starter motor rather than the rings themselves.

What does it feel like turning the engine over on the starting handle?

Stephen

Thanks for your replies.
It is a new starter motor but will check the battery and give it a good charge and try again.
The engine is still out of the car so a bit difficult to use the starting handle but using a spanner on the crank pulley it can be turned quite easily and smoothly, although with some resistance,without plugs.
With the plugs in it can still be turned but the 4 compressions can be felt very strongly and flips the spanner over compression.
It is just about possible to turn the engine using two hands on the pulley without plugs but it does take some effort.
The engine is full of oil and makes 40lbs of pressure when cranking on the starter motor so I am thinking that i might keep regularly turning on the starter over a period of time to see if it loosens up a little.
Thanks again.
Joe.

Stupid question but presumably the engine is all assembled with rocker gear in place? Otherwise the valves can't open! Also rocker gaps correct because if way too big the valves won't open properly. Not sure what the 40 Lb figure means? Do you mean 140 psi compression?

Stephen

I assume you mean 40lbs oil pressure when cranking ?
The resistance sounds normal using a spanner.
So will it crank with fully charged battery, new starter and good connections . If its out of the car, where are you putting the connections
Why a new starter motor, would it crank with the original?
Don't assume new means not faulty!

Question: Were all the pistons giving the same extra resistance to turning when installed? If not checked might it only be one piston/bore that is tight? That could mean even just one ring groove not cleaned out properly, thus not allowing that ring to seat properly in its groove.

Back in the 1980s, I had need to chamfer the inner corners of one, or two rings, for a piston that had been, err, hammered by a valve head (weighing over 150g) bouncing around in the cylinder and combustion chamber until the engine seized.

I always check the resistance for each piston - it is often listed in the assembly specs.

Hope it is the battery or the starter motor - but do check all electrical connections and voltages before jumping to conclusions re either.

The oil pressure is 40psi when cranking.
All valvegear is in place and set to 12 thou.
Each piston had a similar resistance when fitting but the new rings were quite difficult to compress with the ring compressor.
The starter was a new spare I had and seems ok but I am using jump leads to connect to the battery and these may not give the best connection.
I will make up a new set of battery leads and put a solenoid in circuit and try again.
Thanks again.
Joe.

Just rebuilt my engine 1098 and experienced similar to you when trying to crank with jump leads when engine out of the car. Decided to wire up and cranked fine.

If you’ve painted the engine be aware that this may affect your starter motor electrical connections. The motor itself earths through the body of the starter motor via the mounting bolts and metal contact of the end plate to engine back plate.

Stephen

What you describe is typical of a newly rebuilt engine.
The problem of turning the engine over when the plugs are fitted indicates that the problem lies outside of the rebuilt engine.
Make sure that the starter electrical circuit is good.
Did you re-bore the block to the pistons supplied or have the block re-bored and then obtained the pistons/rings. The block must be re-bored to the pistons as we do not have the luxury of graded pistons as they had on the BMC engine production line.
What did you set the ring gaps to?
Did you check the piston gap/clearance in the bores?

The block had been re sleeved back to standard with new pistons as part of a gold seal rebuild prior to my ownership and from measurements of both the bores and pistons and visual inspection, has seen very little running time.
With the original rings the engine turned over very smoothly.
I have ordered the parts to set up a proper starting system, ie solenoid , battery leads etc and I will give it another try with a fully charged battery.
At the moment the engine is sat on a low trolley so I might try and raise it so that i can make full turns with the spanner without it hitting the floor. It may better if I can get some momentum going.
Thanks again for all your valuable assistance, I will let you know the outcome.
Joe.

You could wire it up with a switch that acts in place of the ignition switch or if it is a push-button solenoid you can operate the starter that way. Remember the body of the solenoid needs a connection to earth if you are going to operate it via a low power circuit like in the car; this is provided by the mounting screws when fitted in the car.

Stephen

You don't need a solenoid just a charged battery and jump leads.
Negative from battery to earth, clean connection on engine block any convenient point.
Positive jumper lead to supply terminal on starter.
Now touch other end of Positive jump lead to positive terminal on battery, then engine should now crank

Good news. With a “proper” starting circuit setup and not using jump leads the engine is now turning over happily on compression.
Compression is even across all four cylinders at above 175psi.
Thanks to all for the advice and encouragement which is so important when carrying out restoration work.
Cheers.
Joe.

Good news, now the running in period