Rebuilt 1275 engine, losing oil

[akuchanny]

Hi all,
I have just finished the rebuild of my midget 1275 and got it in the car, on the run home, I got from Bristol to reading with no problems, then the oil pressure started to drop, and I pulled over, the engine had developed a leak that looks like from behind the front engine plate, that is spitting with central fugal force the oil out of the sides. I refilled it but in a even shorter distance, 20/39 miles had to pull over again and refill. Apart from that (well the diff ratio and box need changing) it runs really well.

Any ideas as to why it would just suddenly let go? Also is there an easy way to fix it without having to get the engine out of the car again, i don't really want to borrow a crane again.

I guess on the plus side it has rust proofed the chasis legs again.

[IslipMinor]

Couple of things to check - is the rocker cover filler cap the 'vented' type and is the breather hose from the timing cover connected to the carburettor (assuming you have one with a breather connection?)? Do you have a picture of the engine bay you can upload?

After that an oil leak at the front is most likely one or more of three sources - timing cover oil seal, timing cover gasket or front engine plate gasket. No need to have the engine out to fix any of them. When you rebuilt the engine what did you replace at the front?

Can you clean up the front of the engine, top up the oil and start the engine on idle and see where the oil is coming from? When you say 'spitting out from the sides', do you mean spinning off the crankshaft pulley? If so, it sounds like the crankshaft oil seal, but with enough leaking from somewhere else, it is not the only option.

[bmcecosse]

Crank oil seal is the most likely source - hopefully it's a proper rubber lip seal and not the early felt ring!! As Richard describes - you MUST make sure the 1275 engine is really well ventilated - we will argue endlessly about the leaky cap - but the principle of good negative pressure venting is without any dispute. The timing cover must have a 'breather can' (which must be clear and not blocked with crap) and this MUST be connected to the carb side inlet. Try a new crank seal - and be sure to 'centre' the timing cover on the damper pulley before tightening it all up. The gasket never leaks unless the fixing screws are stripped in the front plate. What 'reconditioning' was done on the engine?

[akuchanny]

The engine was stripped completely and fully rebuilt, with original size (new) pistons and rings, as well as a full set of bearings gaskets and seals. So was a total rebuild.

It has new silcone breather hoses going from the front breather to the rocker cover and carb, which a vented oil filler cap. The oil leak looks like it is coming from the front plate, between block and plate. Although I had to replace a fuel line on the hard shoulder today as it decided to develop a hole, so have left it alone after that for the day today. I have no idea why a gasket would fail so quickly and it has a new front rubber oil seal for the crank that is not showing any signs of oil escaping.

I will try and get some pictures up tomorrow.

A.

[bmcecosse]

If it wasn't rebored and the crank reground - it's not 'reconditioned' - just 'refreshed'. Hopefully the problem is not pressure in the crankcase - were the bores at least glaze busted/honed ?? . VERY unusual for that gasket to fail - in fact - hard to see how it could fail really.. You will just need to strip it down and see what's wrong. It's not oil streaming down from the cylinder head (oil passage rivet/plug) or the head/gasket seal - or even just from the rocker cover gasket?

[JOWETTJAVELIN]

You need to pinpoint exactly where the oil is coming from. This means wiping everything clean and laying on your back underneath, with a bright torch and some eye protection, with the engine running hot - the oil is at its thinnest.

It may be a case of merely tightening a few bolts, or the front plate might have to come off if the gasket is in any way suspect.

I must say that this is the most serious crankcase leak I have ever heard of, and wouldn't even drive the car until it is fixed.

[les]

If we're talking about the timing chain cover, the face can get very distorted instead of being flat. If that is the case it would tend to throw oil about. When you remove it lay it against a piece of glass and see if you see any gaps between the screw holes.

[bmcecosse]

Unless the bolts weren't tightened - it really CAN'T be that gasket..... But yes - ^^^^^ - if the timing cover is distorted that's a possibility. Or is it damaged where the breather cylinder attaches? Or - has duplex timing been fitted - and rubbed a hole in the cover???

[Roni]

What about the plug in the front of the oil gallery? There is lots of oil pressure behind that.(Centre of the photo)[frame][/frame]

[bmcecosse]

Yes indeed - good possibilty !

[akuchanny]

The plug looks intact, most of the oil seemed to be coming from the other side. I did find on draining the sump today that the bolt was loose, so loose I could undo it by hand, so have tightened with a new washer. I have ado cleaned the engine bay, and an ready to refil and check tomorrow exegeses it's leaking.

I have had really erratic oil pressure readings, so am hoping that it was down to the sump bolt changing the pressure in the system. But that dosent explain where the oil has gone or how it's covered the bay.

Well now it's clean I will refill and see where the leak is. Will let you all know when I find the bugger.

[bmcecosse]

Sump bolt can't influence oil pressure........ It should be pretty much solid 70 psi with a decent engine. Perhaps down to 25 at idle when hot.

[akuchanny]

Well filled the engine ran it at idle for about 20 mins only a few drops from it. Was holding a steady 20lbs during this time. Took it for a run, in the space of about 3 miles oil pressure was dropping. Then idle was around 15lbs at 50mph was down to 35/40lbs. No sign of a leak this time. And the dip stick although being difficult to read with clean clear oil, seemed to show no change, but will test it properly when I'm on a flat surface, not the cambered car park I was in. Still stumped by this. Could it be a duff oil pump?

[bmcecosse]

That oil pressure is desperately low - FAR too low to drive. Presumably you fitted a new oil pump - but have you checked the relief valve?

[akuchanny]

Further update, I just arrived home, and there is a leak, it looks to be from either the front plate and block (as first guessed) or the timing cover to front plate. But surely as the leak dosen't look substantial it shouldn't drop the pressure so quickly.

[bmcecosse]

Leak has nothing to do with low oil pressure - at least - not until the sump runs so low the pump can't pick up. Did this happen when you had loose sump plug?? If it was run short of oil - the bearings may be ruined. You have two separate problems here - low oil pressure (extremely serious) and oil leak (minor, but annoying of course).

[akuchanny]

Haven't checked the relief valve, its still in position and shows no sign of oil escaping through it.

I'm guessing it would mean pulling it out to fully check it?

[akuchanny]

The pressure was holding during start up and idle, it drops under load and then stays low. The bearings should be fine, they are new and have only run for around 170 miles max. it hasn't been run for any period of time with no oil in it, even with the pressure issue from today, the oil level is still good, but admitiadly that was only a short run, but I'm pretty sure that the oil level has been fairly consistant now, especially after draining the sump yesterday, and finding that it was still holding enough oil to almost full the catch can to the correct level. The loose sump plug was alarming, but now there are now pools under the car. Just leaking from the front being pushed down the block. What would cause such a drastic pressure issue, on a engine that was running well with good pressure for the first 70 miles, and then poof, it's gone.

[IslipMinor]

The symptoms you describe are very mixed - can you list exactly what has been done as part of the engine rebuild, including the work that was done and all the parts that have been replaced? Is the engine quiet when running?

As has been suggested earlier, you need to clean the engine thoroughly, make sure that it is full of oil and then get underneath while the engine is started, so that you can identify the first sign of the oil leak. You will probably need to repeat the process a number of times to make sure that you have identified the real source, and not just somewhere it is dripping from.

What was the condition of the engine before this rebuild? What prompted you to do it?

[les]

Start with the relief valve, undo the cap and inspect the plunger for scoring or muck holding it off the seat, check for a broken spring, although unlikely if rebuilt. Forget the leak for a while, it's the pressure you need to sort out. I wonder if the pump is worn and when the oil gets hot and thinner can't hold pressure. Although would you have used the original pump?