oil in the exhaust

Mike Usiskin · Post by **Mike Usiskin** » Mon Jan 02, 2006 5:33 pm

Hi all,

it would appear we have a problem.....

car's up and running, ye haaaaar i hear you say, well yes and now no.

Had a good run yesterday 100 + miles or so, 4 up, no troubles. when I park at home later on the neighbour pops over to tell me "that red thing of yours is leaking, why not buy a mazda!!!!!!!!!) I promptly say say thanks I'll look at it and then forget completely, it's new years eve for gods sake.
Today i start her up, sounds fine but rear view mirror very cloudy, i get out to see blue smoke, not all condensation, increasing with revs. I turn off the engine, wait for it to cool (moments, I'm impatient) and have a look. Now, I can't see anything wrong but there is oil lying in the bottom of the exhaust pipe, which can't be right

What to do folks, possible causes etc,

oh yes, Happy New Year

Mike

bjmullan · Post by **bjmullan** » Mon Jan 02, 2006 6:48 pm

It's either a rocker cover gasket or one of your oil return tubes is leaking. If it's not a great deal of oil then I would start the engine again and get underneath and have a look as oil is being pumped around the engine.

hot66 · Post by **hot66** » Mon Jan 02, 2006 7:55 pm

is it 'IN' the exhaust pipe or around it?

Are you deffo sure its oil & not 'sooty water' or unburnt fuel?

Mike Usiskin · Post by **Mike Usiskin** » Mon Jan 02, 2006 8:25 pm

Hi tim,

Happy New year

it's IN the exhaust pipe!

Deffo oil

mike[/i]

impmad2000 · Post by **impmad2000** » Mon Jan 02, 2006 8:41 pm

I'm Tim, That's James

Have you filled the oil correctly ? Level check only when running and HOT !
Are you running the same oil as you have always used or switched to a nice new thin synthetic ? Oil could have run down a worn valve guide, perhaps.
I can highly recommend a Mazda

Cheers
Tim

Barry · Post by **Barry** » Mon Jan 02, 2006 8:42 pm

Mike: I would get hold of a compression tester, and test all of the bores: I would think chances are that it could be a piston ring that's gone. If the compressions are fine then

a) Valve guide seals (pretty unlikely to be enough to stay in exhaust)

b) Blocked oil breathing (very, very unlikely)

c) Scavenge side of the oil pump not clearing the oil quickly enough

d) Very short runs plus worn oil pump could lead to too much oil collecting in sump bottom (during days not run), and then being forced past rings at the beginning of journeys, until scavenge catches up.

Order of diagnoses (if it was me)

1) Compression test: if fine then probably safe to continue running the car.
2) Check oil level in tank before starting (i.e after left for a few days): you may have to use a piece of wire (e.g. clothes hanger) as it may drop below dipstick level anyway. Obviously if a large percentage of the oil tank contents have disappeared, only to reappear after a run, then the car's wet sumping. I'm not sure what would be normal though

.
Also make note of engine oil presure under various conditions: again if it's low throughout, might point to wet sumping.
3) If still nothing obvious, and the comps. are fine, and the oil pressure is good (or at least not too bad) I would take the car for a reasonable run, stop when it's roasting hot, wipe the exhuasts out, then carry on with the journey. If you arrive home to find them clean, you know the problem is standing/short journey orientated.

Nothing very clever there, I'm afraid (

) but HTH nevertheless ....

Barry · Post by **Barry** » Mon Jan 02, 2006 8:44 pm

Hello Tim, you just beat me too it!

Mike Usiskin · Post by **Mike Usiskin** » Mon Jan 02, 2006 9:09 pm

Hi all,

the oil was changed for nice new spangly synthetic stuff, 5w40 to be exact. I used to use 20w/50 but was told not to as it's too thick for anything other than agricultural machinery. not sure how much to trust?

Could it be overfilled, though very unlikely as the car was seen by Peter Freidman at Nos 5 Garage.

hmmmm

I'll have a better look in the light tomorow, as well as pictures of seatbelts etc.

thanks for the advice thus far.

Grrrrr, i just want to drive the thing !!!!!

mike

davidppp · Post by **davidppp** » Mon Jan 02, 2006 9:38 pm

Hello, Mike.

Barry is right on the money as usual IMHO....

What is the history of this engine though?

Valve guide wear or seal failure are common cuases of quite smokey starting, which improves witha good thrashing...

Rings do NOT improve...

Best of luck..
David

Barry · Post by **Barry** » Tue Jan 03, 2006 2:23 pm

Hopefully the change to synthetic might be the problem (I'd still do the above though: you don't want to cause any damage to anything). I think a lot of people use various 20/50's, I personally used Redline 20/50 from Delta oils, but I did have to re-mortgage each time

.

When it comes to oils, I've always felt that your oil pressures will tell you what the engine is happy with. If you were running your 5/40 (say), and you are getting 15+ psi pressure at idle, and 15 per 1000 revs (ish) then you are probably safe with that (thinnish) oil. On the other hand, if you find that your idle oil pressure is almost non-existant, the running pressure is a bit low, and that the scavenge pump struggles to keep the oil in the tank (rather than the sump) then a thicker oil would probably be more appropriate.

Either way, as Tim rightly says check the running oil level, and still check those compressions. If nothing else, it is a good discipline to do a compression check on any 'new' car. Keep a note of it, then when you (or your man what does

) service the car, re-check them: you will be able to see how they are holding up. If one was a bit low when you bought the car (for instance) you may find that it simply stays the same, in which case take no action. On the other hand if it's tailing off quickly, and you're heading for the winter you know that it's a job to be dealt with in the short term. I'm rambling. I'm going to stop now. Goodbye ...

Barry · Post by **Barry** » Tue Jan 03, 2006 2:47 pm

Forgot to say: he who says that 20/50 is for agricultural machinery only must be a) Brave b) Ill informed.

We all know that the temperatures of air/oil cooled engines is far, far higher than watercooled. The thermal shock to the oil as it hits the cylinder head area is much greater, as is the underside temperature of the pistons (again cooled by oil jets on most models), as the cylinder wall is taking much less temperature out of the piston. Therefore many oils are running towards their upper limits.

The early cars (2.4 and earlier?) have pretty small oil pumps, many of which are now probably getting past their best, and require a thicker oil to maintain pressure.

I could go on (as you know

) but the bottom line is that our cars are now of an age where sweeping statements for oils just aren't appropriate. You may have a recently rebuilt early engine, with upgraded oil pump and oil cooler, which could well be very happy on a thin oil. On the other hand you could have a fairly worn engine, running an elderly, standard oil pump and just a standard oil cooler. Clearly this engine would have very different needs. Bottom line: I would always go by the oil pressure: if your's holds a good oil pressure and temperature then you are running an oil that suits your engine. If you've got low oil pressure, high oil consumption and tend to have higher temperatures then its time for a change.

That's really it now: I'm going to play in the workshop

.

Mike Usiskin · Post by **Mike Usiskin** » Tue Jan 03, 2006 3:28 pm

Hi Barry and all,

Many thanks for all your advice, I'd be Bu**ered without it

Ok the story so far...

This morning I started her up, expecting loads of smoke but no, nothing other than normal wet weather startup stuff, so I warmed her up to 180 ish, approx 10 odd miles though town , then checked the oil. Leval was right on the money, perfect, I figured i'd take a little out anyway so used the trusty syringe I never thought i'd need (brought for £2.00 in a car boot sale) to take out just under a litre. All seems happy but i'll check after she's cooled to see if she's leaking and if so maybe change the oil for something thicker.
At the moment she's running when warm (180) just under 20 psi at idle (so possibly 15

) and 60 psi at 4000 rpm so according to your info she's about right.
My 'man' (love that, sounds great) did say that we could run her on what he calls "high mileage oil" if she doesn't like the posh stuff. From the numbers above she seems to be happy though si I'm tempted to leaver her alone and see how she does.

Any thoughts?

Thanks again

Mike

Barry · Post by **Barry** » Tue Jan 03, 2006 11:17 pm

Mike, if its not already been done, it's got to be worth pulling all of the plugs, and seeing if any of them look particularly oily: might give a clue. If not, two words: Check and Compression

.

Testers are not expensive, just make sure that if you buy one (recommended) that you get one that can reach down the plug hole: I borrow my Dad's one: it's an obsolete make but the important bits are:

a) Its got a long flexible neck, with the dummy plug on the end: i.e. it screws into the plug hole: some of them used to have a rubber cone that you pushed into the hole: trouble is it's not very positive and you need two people to operate it.

b) This one has a positive lock: as it pumps up, the 'gauge' (actually a bar in this case) positively locks, so that it records the highest reading, until you positively cancel the reading.

Just for reference, when you do a compression check the important thing is to always carry out the test in the same way. Usual practice is to test from stone cold, throttle wide open, and crank until the pressure goes no higher: usually shouldn't take more than four or five compressions to find it's level. Only thing to note possibly is whether you removed all of the spark plugs, or just the one on the cylinder you are testing (affects the cranking speed slightly: not enough to really make a difference).

When you've done the test, you are mainly looking for differences between the cylinders, within 5% is (I think) considered pretty good, and 10% just about acceptable. To give an idea, my little 914 differs by 3 psi between all cylinders, which I'm very happy with (pure luck I think).

Good to hear that your oil pressure sounds very healthy, although you may find the temperature goes up, and the pressure falls a bit in the summer: either way, at least you have the option of several acceptable 'thicker' oils 'in reserve': no bad thing at all

.

If you've got clean plugs, and good compressions, coupled with a very nice oil pressure, I would rest easy and enjoy the car. When you think about it, really you would expect huge billows of smoke if the engine was chucking out enough oil to sit in the tailpipe(s) so hopefully you will only find evidence of a healthy engine

.

Barry · Post by **Barry** » Tue Jan 03, 2006 11:23 pm

Me again, just realised I've put a misleading statement earlier:

Hopefully the change to synthetic might be the problem

What I was refering to was the fact it was a thinner oil, not that it's synthetic. I'm sold on the principles of synthetic, particularly on aircooled engines: just not an automatic assumption that because its synthetic, you use thin grades.

I humbly apologise to the House for the error of my ways, and await my punishment ....