smoke on over run :-(

sidecar · Post by **sidecar** » Tue Dec 29, 2009 4:50 pm

thev8kid wrote:

i was hoping some one was going to say, put x amount of psi in the cylinder and watch for the following

I have a Sealey leak down tester that you can borrow if you like, I live in Bagshot, Junction 2 of the M3.

Post by **Coops** » Tue Dec 29, 2009 5:04 pm

sidecar wrote:
thev8kid wrote:

i was hoping some one was going to say, put x amount of psi in the cylinder and watch for the following
I have a Sealey leak down tester that you can borrow if you like, I live in Bagshot, Junction 2 of the M3.

cheers mate will bear this in mind,
im gona have a go at making one first,
failing that may borrow yours or buy one i got my eye on on good ole ebay,

sidecar · Post by **sidecar** » Tue Dec 29, 2009 5:34 pm

thev8kid wrote:
sidecar wrote:
thev8kid wrote:

i was hoping some one was going to say, put x amount of psi in the cylinder and watch for the following
I have a Sealey leak down tester that you can borrow if you like, I live in Bagshot, Junction 2 of the M3.
cheers mate will bear this in mind,
im gona have a go at making one first,
failing that may borrow yours or buy one i got my eye on on good ole ebay,

No problem mate, I'm sure that you can knock one up without too much bother.

Mine has two gauges, I noticed that the one in the link that you posted has one, not sure if it matters much.

Post by **Coops** » Tue Dec 29, 2009 5:40 pm

got me eye on this one,
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... ink:top:en

sidecar · Post by **sidecar** » Tue Dec 29, 2009 6:08 pm

thev8kid wrote:got me eye on this one,
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... ink:top:en

That's the one I've got!

The only problem with it (and I suspect others) is that it is a pain in the ass getting the spark plug adaptor in place and tight. In the end I've made a couple of my own from spark plugs and some steel tube.

As you are testing the rings and the bores a handy tip when using the tester is to remove the rocker shafts so that all of the valves remain totally shut. It is then very easy to bump each piston round to TDC (use a screw driver down the plug hole). I bump the engine round by jacking one drive wheel off the deck, putting the box into first gear then use the wheel off the deck to turn the engine. (Or at least I could use this method until I fitted an LSD).

You can use the leak down test to check for other faults such as leaky valve seats, blown head gaskets etc although that is not the problem that you've got.

mgbv8 · Post by **mgbv8** » Tue Dec 29, 2009 9:19 pm

I lost the instructions to my snap on leak down tester. But you csan borrow it if you want Coops!!!

I'm sure the instructions are on the net somewhere.

I normally just hook it up to each cylinder and go listening for air at the tailpipe, filler cap and carb !!

ramon alban · Post by **ramon alban** » Tue Dec 29, 2009 10:35 pm

thev8kid wrote:thing that confuses me is if its that bad why is it not burning oil any other time? ... normal driving etc no oil burning,

and the comp test was done two days after the car had run and was cold

Tony, I thought I'd explained that massive overrun vacuum (and maybe even lots more on your arrangement) sucks oil upward if there is (scraper) ring/bore damage, so the oil passing though the hot engine/exhaust is only partially burned giving a typical blue smoke, indicative of little or no actual (black) oil burning.

Whereas:

Under normal driving conditions there is little or no vacuum to suck up oil and the combustion process is near normal if the compression rings are OK, except perhaps some increased blow-by may create excess breather fumes.

Regarding the compression tests being done when cold! You might have done the cylinders in sequence so # 4 was fourth and # 8 was eighth or maybe you just started from the front and they were both done last, giving plently of opportunity for any oil thereabouts to dig in and cloud the results.

If perhaps you had done # 4 or # 8 first then maybe you could see a diffo result!

Further, if the compression rings are all OK but the two particular oil scraper rings are not OK, this may form the explanation needed.

The above also goes some way to address the point made by katanaman, but I am also very mindful of the fact that I heve never had any experience in stripping or maintaining these RV8 engines below the heads. Like NIL. It's only the thoughts inside my head that are keeping me going.

Post by **katanaman** » Wed Dec 30, 2009 1:15 pm

Yes it is a fair point on the oil control rings right enough. If something has happened to them you would get good compression but still have burning oil problems. Personally havent had any experience of these going bad without other problems like worn bores. Only way I can think of these getting damaged on a new engine is when the engine was put together. Unlikely on a new factory engine but not impossible I suppose.
My leakdown tester is an old sparkplug with an airline click on connector welded on, a gauge and a quarter turn tap. Nothing fancy but it does the job. I think RS does a kit as well.

Post by **Coops** » Wed Dec 30, 2009 1:39 pm

oh i tested 2.4.6 and 8 first as they were the easiest to get to

bigaldart · Post by **bigaldart** » Wed Dec 30, 2009 10:01 pm

A leakdown tester is just a controlled orifice 40 thou or 1mm is the standard ideally mounted between two 100 psi gauges with a regulator attached. Just set 100 psi on the compressor side and read the other gauge the difference is the amount of leakage. If more than 10% try just nudging the piston slightly to seat the rings and observe any change. By the way piston is at top dead centre. By listening around the engine you can determine where the leakage is, throttle body/ carb its an intake, exhaust pipe, exhaust valve, breathers, ringsl. Think about escape paths and you will get it. for a fresh engine I would want less than 5% leakage, anything 2% or under is perfect. I would not worry about 10 or 15% on an engine that had a few passes on it, unless it was leaking at the intake valve. Thats only because of the supercharger and potential for a big BOOM if the intake valve failed.Do it the right way, any of the commercial testers are either one gauge which has an internal regulator and reads directly, or two gauge as described. If you make your own its not difficult just look it up on the web. Can be bought for around £100 or less so way cheaper than an endoscope which is much more difficult to interpret. Sorry for being wordy.

Alan

unstable load · Post by **unstable load** » Thu Dec 31, 2009 6:16 am

Pretty much as Alan says, but I will add that when turning to TDC, if you overshoot then go all the way around again as the rings need to be bottomed in their grooves to give the best seal they can. ie, do not turn BACK to TDC if you overshoot.

Good luck, mate!

Post by **Coops** » Thu Dec 31, 2009 4:09 pm

just ordered the sealey leak down tester i linked to the other day,

going to do the leak down test first,
for some reason im thinking i got a couple of faulty stem seals, (were replaced before going onto the 4.6)
they have not slipped off there seats,

can you use the leak down method to keep the cylinder pumped up to remove the valve cap?

bigaldart · Post by **bigaldart** » Thu Dec 31, 2009 6:06 pm

Normally with the sort of springs Rovers use the air will be enough to change the retainers or springs. If doing that I would have someone hold the crank steady or wedge it with a rag or something to stop the engine turning.

Alan

ged · Post by **ged** » Thu Dec 31, 2009 6:43 pm

Hi Tony,

The last time I did it I made up a bar that located on the rocker shaft bolts for compressing the springs & only used 5-10psi but as bigaldart has already said lock the crank or put it in gear.

Regards Ged.

mgbv8 · Post by **mgbv8** » Thu Dec 31, 2009 8:34 pm

Coops!
It is easy to knack the knock on seals. I've had a couple that went a bit oval. They distorted as they pushed down for some reason. They didnt come off. But they didnt seal well either.
And those stupid little springs !!!
You have to check that they dont pop off as well eh??

Happy New year all !!

Perry