Difficult to crank engine

[jandarah]

Hi, I have two 1756cc engines, one in a road Spider and one in a recently aquired 124BC coupe, used for sprints and hillclimbs. I have started the coupe engine only a few times, as I have been tidying up the wiring and body. It is supposed to have a modded cam. The other day it started ok, ran rough and stopped a number of times. It is now very difficult to crank with the starter and a charged battery. Even with the plugs out it is hard. Hand cranking it with a socket and breaker bar on the main pulley is hard and tight, even with the plugs out. For comparison, I tried the same on the Spider and, by hand, it was nice and free with plugs in. Now, all pistons are moving up and down (tested with drinking straws placed down the plug holes). When cylinder 4 is at TDC, all timing marks line up.

Now, where should I be looking? Oh, the oil had not been changed by the previous owner for however long and looked like black water, so I changed both oil and filter. I know this will cost money, so it won't surprise me.

Thanks, in anticipation,

[baltobernie]

... the oil had not been changed by the previous owner for however long and looked like black water ...

Water-like consistency? That might mean the PO tried some kerosene or diesel down the cylinders to free a frozen motor. If you can't turn it by hand with the spark plugs removed, that engine may be toast. You might try temporarily removing the fan belts, in the hope that a seized water pump or alternator is preventing free movement, but that's a long shot. The car rolls OK in neutral?

[bluespider262]

Really thin oil can be caused by fuel contamination too. Ruptured diaphragm in the pump or possibly a needle that isn't shutting in your carb, or improper float a adjustment. Or maybe too much fuel pressure blowing the needle off the seat.

If you get it to fire again see if you can see fuel dropets or a steady stream into the carb. Either one = rebuild time and it will probably run much better once it isn't running super rich.

An engine with good compression won't really be easy to rotate. It'll take some effort. How does it feel relative to your other motor?

[jandarah]

Thanks for your replies. When I said that the oil looked like black water, it might have been a bit of an overstatement. Yes, it was very black and its viscosity was minimum. It did look like oil that had been around for a while in an engine. I have driven this car previous to my purchasing it, but around the block. I have moved it about my premises, onto and off stands, on and off a car trailer for its journey home and on and off when it was recently repainted. As it is not road registered any more, its movements are limited. All previous times, it started fairly easily. Once it had warmed up a bit, it started first go. It has never been worked hard by me. The previous owner was elderly and was retiring from driving in sprints and hill climbs. As there are not that many events in this part of the world, it would not have been overworked.

It does have twin Weber 40 IDF's. They are fed by an after-market electric fuel pump in the engine bay.

I have have hand cranked my Spider with the same socket and breaker bar on the main pulley and it moves easily. This one, even with the plugs out, is quite hard and stiff to move. (I must add that the bottom saddle that holds the radiator in the coupe is in a terrible spot and very close to the main pulley and nut, when compared to the Spider. This makes hand cranking of it a pain, as it is hard to fit the socket over the large nut.).

I might loosen/remove the secondary belt to the alternator and water pump and see what happens. Wouldn't it be nice if there was an issue there?

Thanks again.

[RRoller123]

Has the timing belt still been installed when trying to turn it by hand?

[jandarah]

Hi, yes, everything is in place as it should be. Both belts are in place and timing marks are lining up when cylinder 4 is around TDC. Could it be in the head..... valves etc?

[RRoller123]

It sounds like something in the engine has seized, possibly crankshaft or cams. Although if it is a cam, turning the crankshaft would cause the belt to slip on the cam sprocket and jump teeth, which would then introduce interference problems. Clutch is fully releasing the transmission, and it is in neutral?

[jandarah]

Well, I played with it again today. With the plugs out, I first checked the water pump and alternator movement....... alternator good, water pump good in one direction ( I guess that's normal). Cranked the engine with no plugs and loose secondary belt. It cranked, but not fast. Installed the plugs and it would not turn at all. So, back to square one. Yes, it was in neutral and I am sure that the clutch is releasing correctly. .......????