19 replies to this topic

[zero_wlv]

Just going back to the oil consumption, have checked it on the overrun?

 

Does overrun refer to accelerating after driving down a steep hill?

 

If so,  I have kept a look out to see if I can see any blue smoke (or ANY smoke) from the tailpipe under that condition and I can't.

I can't see any smoke from the tailpipe under any other conditions either  (other than a small amount of thin white vapour which I would think is normal in winter).

I suppose I could get someone to follow me and have a better look.

 

 

One thing has just occurred to me which I haven't yet mentioned   -   the tappet case breather is just vented straight into the engine bay,   rather than connected to the carb or air filter.

This is how my previous engine was when I bought the car so it didn't really occur to me to have it any other way until I read a few threads mentioning breather systems.

I don't know how much practical difference this can make to oil consumption but I've ordered the hose and might try connecting it.

[Northernpower]

Just going back to the oil consumption, have checked it on the overrun?

 
Does overrun refer to accelerating after driving down a steep hill?
 
If so,  I have kept a look out to see if I can see any blue smoke (or ANY smoke) from the tailpipe under that condition and I can't.
I can't see any smoke from the tailpipe under any other conditions either  (other than a small amount of thin white vapour which I would think is normal in winter).
I suppose I could get someone to follow me and have a better look.
 
 
One thing has just occurred to me which I haven't yet mentioned   -   the tappet case breather is just vented straight into the engine bay,   rather than connected to the carb or air filter.
This is how my previous engine was when I bought the car so it didn't really occur to me to have it any other way until I read a few threads mentioning breather systems.
I don't know how much practical difference this can make to oil consumption but I've ordered the hose and might try connecting it.

No overrun is foot off the throttle while still in gear and under load, you can do this by going down a hill in gear with no throttle. This will mean the cylinders will suck from other areas i.e. past the the valve stem oil seals. Look behind or if you're not going too fast open a window and you may be able to smell it as it gets sucked back into the cabin. I know this from personal experience.

[ACDodd]

Mike spider, I completely disagree. Who in there right mind leak tests and engine at bottom dead centre? They are always completed at TDC. Useful comparisons can be drawn between top and bottom dead centre in terms of bore wear. Since the engine should seal better at the bottom as opposed to the top. It will also take longer to pressurise at the bottom since the bore volume is much larger. The problem is on most engines testing at bottoms dead centre is not possible because the exhaust valve is already open at this point.


Ac

Edited by ACDodd, 25 January 2018 - 08:01 AM.

[evoderby]

Well he is down under you know.
.
.
.
.
.
.
.
.
I’ll get me coat

[Spider]

Mike spider, I completely disagree. Who in there right mind leak tests and engine at bottom dead centre? They are always completed at TDC. Useful comparisons can be drawn between top and bottom dead centre in terms of bore wear. Since the engine should seal better at the bottom as opposed to the top. It will also take longer to pressurise at the bottom since the bore volume is much larger. The problem is on most engines testing at bottoms dead centre is not possible because the exhaust valve is already open at this point.


Ac

 

Sure, but it's still a static test. It doesn't mimic what's going on when it's in a dynamic state, which it's in when running.

 

<Edit: if you can get meaningful results from Leakdown Tests, that's great, but I've seen quite a number of bum-steers been given by this test and for the reasons set out >