General Oil leak

[ozza]

Hello all,

I'm finding my 71L original engine very oily in the engine bay (had the car 3 weeks).

Gave the whole engine a clean & degrease the other night and then took it for a run today, about an hour of driving all in I suppose.

The oil seems to witness from the top of the engine and show splattering over the distributor and coil area.

There was also some oil on the back of the car as it had sprayed through the rear engine cover vents on the off side.

Other things to note are when I replaced the air filter I found some but not lots of oil in the air filter box that had come from the breather pipe by the filler cap. Under running with the cap off there seems quite a bit of pressure in the rocker cover but maybe not more than you'd expect (I'm not exactly sure what to expect!).

I believe the engine has had new piston rings in the past.

So are there any 'usual suspect' areas to check on these motors. I'm thinking the rocker cover gasket as a possible?

Cheers as ever for any advice.

Ozza

 

[fiat500]

You're thinking right about the rocker cover. People overtighten and the gasket gets pinched and at worse, the cover gets distorted.

I think there can be a certain amount of back-pressure...two pistons going up and down at the same time. It's worth taking off the airfilter end of the narrow rubber pipe to check if there's a coiled, metal; flame-trap in there...there should be.

Both your symptoms might also be too much oil or too thin an oil.

I would replace the gasket and see how you go.

 

[Vitesse]

And of course the dipstick is an old favourite, they do have a tendency to pop out under pressure and if really loose they will just sit back down where they came from after the engine is switched off.

Tony

 

[fiat500]

Surely you could do a full page feature on oil leaks after sorting that 650 Tony?

I also forgot to suggest the filler cap which can be vey tight and hard to secure properly or very loose and missing the gasket. My filler cap also had a small leak where the central "stud" is sort of rivetted in.....fixed with epoxy.

Interesting that Ozza mentioned piston rings because all this is worse in a tired engine.

Are you doing to tell him about the pushrod tubes?:bang:

 

[Vitesse]

I immediately thought pushrod tubes but they are on the other side of the engine but TBH as you can't see them behind the tin work then they can still spray oil around and give the impression it is on the opposite side.

The 650 had a dodgy filler cap that was loose as well, it would sort of twist on and lock off but still rattled around. It was fixed with a bit of bending the lugs and a new gasket.

It does sound like quite a substantial amount of oil leaking, so I would have thought rocker box cover, oil filler cap or dipstick would be the first port of call?

Years ago mine had the popping dipstick and it went everywhere including all the vents on the engine lid.

 

[Bambino]

I'm told that given the dipstick seal is OK, a popping dipstick is symptomatic of worn rings that permit over pressurization of the crankcase. Must be an impressive sight when the dipstick flies out on a jet of oil as the engine starts. Similar to the geyser of water out of the radiator with a failed head gasket.

If rebuilding, these engines can be made oil-proof. Part of the method is checking the mating surfaces for flatness.

I have a friend with an old Jag and despite a rebuild it still drips oil. His wife asked sarcastically when it would stop fouling the garage floor to which he rather tersely replied 'when the sump is empty ... dear ...'

Chris

 

[ozza]

Thanks as ever for your thoughts guys.

Oil I'm using is 20/50 for classics.

I'll check the dipstick today; wouldn't it be nice if that's all it was but I doubt it.

When I got the car it was on the minimum on the dip stick and a little oily, but not as much as now as I've topped it up to 3/4.

I'll check the filler cap as well but it did seem a good very tight fit and the pressure spring seems to work well.

Maybe I'll drain out a little oil today and see if it helps as well.

If it's not a quick fix then I suppose it's start with the rocker cover gasket and push rod tubes.

I see a cork or rubber option for the rocker cover (it's rubber at the moment) I suppose I should stick to a rubber replacement?

Cheers

Ozza

 

[fiat500]

Hi Ozza, back "in the day" it was always a sort of rubbery gasket that you could actually re-use a few times. Just don't overtighten...that's why it has nyloc nuts. Also, make sure there are fibre wasers under the steel washers.

 

[ozza]

So seeing that the leak seemed to be coming from the top of the engine I hatched a plan.

I covered the top of the rocker with foil and took a short drive after cleaning the engine up.

Then on return checked the underside of the foil. Seems like the oils coming from the back edge of the rocker seal (towards the front of the car and hidden from view).

So next stage is a new gasket I suppose.

Is it just a rubber gasket I need?

If the rocker cover's been over tightened and deformed a little will it still leak with a new gasket?

Ozza

 

[Vitesse]

So seeing that the leak seemed to be coming from the top of the engine I hatched a plan.

I covered the top of the rocker with foil and took a short drive after cleaning the engine up.

Then on return checked the underside of the foil. Seems like the oils coming from the back edge of the rocker seal (towards the front of the car and hidden from view).

So next stage is a new gasket I suppose.

Is it just a rubber gasket I need?

If the rocker cover's been over tightened and deformed a little will it still leak with a new gasket?

Ozza

Ingenious thinking Ozza.

You need the fibre washers as well that Peter mentioned previously. I always use Blue Hylomar on my rocker gasket just to be safe. It should resolve any issues if the cover has distorted a little.

Tony

 

[sheylings]

Ozza

I had just this problem only two weeks ago. For me the oil leak remained with new gasket and it wasn't until I put a new rocker cover on did the leak disappear. It's likely you'll need a new gasket anyway so no harm in trying that in the first instance...

Steve

 

[ozza]

Ok guys, as ever thanks for the info

 

[ozza]

Anyone happen to know the torque required for the rocker cover as I can't readily find it in the Haynes manual and I don't want to over tighten.

ta

 

[Paolo66]

I don't think you'll find one. The nuts should be nyloc type against a steel washer against a fibre washer. I would tighten both down equally until the fibre washers and rubber gasket compress. Start your engine and let it idle and check for leaks. If you get a leak tighten a little more. If you find you're really having to tighten the nuts to the point where you are distorting the rocker cover then you will never get it to seal. With a new gasket, fibre washers and nyloc nuts you should be fine.
Damian

 

[ozza]

Cheers Damian

 

[nzbobc]

Since the cover may have been overtightened, check the area where the nuts tighten down. On my cover, the nuts had been tightened down so much that these two spots on the cover were in the shape of hemispheres and flat washers couldn't get good seals against these curves surfaces.

 

[ozza]

Thanks for the tips.

The rocker cover doesn't look deformed but the gasket did look at little misshapen as if it had short cut one of the corners a little.

I have reseated it and resealed with gasket seal, seems OK so far but will give it a longer run to test.

I have a new gasket now if this fix fails

Cheers

Ozza

 

[Pete145]

And of course the dipstick is an old favourite, they do have a tendency to pop out under pressure and if really loose they will just sit back down where they came from after the engine is switched off.

Tony

Hi Tony, just seen this quote having searched old threads (before starting a new one).

I have a new dipstick (last year) but I also have a very oily engine bay again! I checked the dipstick and it is sitting very loose in it's receiving hole. Any way to 'firm that fit' a little, or is there a particular brand of dipstick that sits firmer?

 

[fiat500]

Hi Tony, just seen this quote having searched old threads (before starting a new one).

I have a new dipstick (last year) but I also have a very oily engine bay again! I checked the dipstick and it is sitting very loose in it's receiving hole. Any way to 'firm that fit' a little, or is there a particular brand of dipstick that sits firmer?

One of my "pet" problems that Pete.
As an experiment I tried an original dipstick which is a snug fit..almost feels magnetic! I think the "O" ring is the key to this. so could you find a better one.
There doesn't seem to be any back pressure in the crankcase of mine, but a worn engine (which yours can't be) would push it out.
Maybe a 126 one can be made to fit. they seem to have a proper rubber collar.

 

[Vitesse]

One of my "pet" problems that Pete.
As an experiment I tried an original dipstick which is a snug fit..almost feels magnetic! I think the "O" ring is the key to this. so could you find a better one.
There doesn't seem to be any back pressure in the crankcase of mine, but a worn engine (which yours can't be) would push it out.
Maybe a 126 one can be made to fit. they seem to have a proper rubber collar.

Agree with Peter the older dipsticks seem to be a lot better than the pattern parts. The "0" ring types that are recommended for the 500 seem to be a really poor fit and don't seem to seal very well.

I can only imagine that Fiat changed it to a rubber collar on the 126 because it solved the issue with poor fitting dipsticks. I can check tomorrow whether the 126 one will fit on a 500 engine as I have one fitted in the 650 engine in the garage and can try it on my 500.

Tony