testing HELP

[Speedtouch]

Yes, though petrol would be better.

[magpie]

looks like that's next then ,great love it!

[driftwood]

I'd try a bit of oil down the spark plug hole before doing any dismantling. See if you get the compression to improve.

[magpie]

how much oil ? and then compression tester straight back in and crank yeah ?

[Speedtouch]

Just a thimble/egg-cup full or so. It will establish whether it's the rings or the valves that are leaking.

If it raises the compression, then it's the rings.

[driftwood]

Not too much. Maybe a dessert spoon's worth or 2. Then cover the hole with a bit of rag. Give it a 10 seond crank with the other plugs out. Put the plugs back in and see if it starts. Try another compression test. You might be lucky and might just have a dry bore. If not, a leakage test will tell you where you're losing your compression before you start stripping.

[magpie]

ok, i've dropped some oil in pot 6 and.......



what next ?

[Speedtouch]

Blimey, quite an improvement!

I would stick the spark plugs back in, fire it up and drive the thing - a few miles should loosen up the piston rings quite nicely...

[magpie]

fired it up and after the smoke screen cleared lol it's just the same with that ticking/clanking noise from pot 6

[magpie]

took it out for a blat round the block to see if somethings going to either break or fix itself,it goes well but sounds like shit and the pressure is right down again with the other plugs left in.



[youtube][/youtube]

sounds worse in the vid but you can make out the clacking that's doing my nut in!

any idea's

[maggspower]

That's not good Mick

The oil that you put down the plug hole has acted as a temporary seal giving you back lost compession, hence the high reading. The oil will not seal a leaking valve.

It only lasts so long though, looks pretty conclusive, you have a compression leak on 6 so it will be the rings, piston, knackered bore or casting, or H/G leak.

Sorry to be the barer of sh1t news.

[DanThe]

Doesnt sound right at all, worn rings dont make that noise, get the cam cover off Mick and check the timing!

[craigieeb]

Did Northern re-bore take the valves out when it was skimmed ??

[magpie]

kk will do it now lol,it's bled up fine and not overheating if that makes any difference ?

[DanThe]

Did Northern re-bore take the valves out when it was skimmed ??

No need on a vanos craig unless its 'very' thin!

[maggspower]

Doesnt sound right at all, worn rings dont make that noise, get the cam cover off Mick and check the timing!

I admit that it doent sound nice on the vid, but its just so hard to tell from a vid. The camera, phone or whatever pick up the noises bounced off ever flat surface so you never get a true sound.

A leak down test would be next if you can get it done anywhere. this will pin point EXACTLY where the compression is going, if the tester knows his onions.

[DanThe]

Simple checks first though

[maggspower]

Simple checks first though

Agreed

But how come all the others are ok? and Mick says it burnt all the oil off then started missing/clacking again.

[magpie]

plumbed it in to TDC and the inlet side looks fine.



this side ?



valves weren't taken out,he said they don't need to be removed

[magpie]

[craigieeb]

If it's not the timing, it's got to be either a bent valve or the rings.

[driftwood]

I think you'll end up stripping the engine anyway but if you do a leakage test 1st you'll find the source of compression loss. You can make your own tester. Was the engine ok before the head work?

[magpie]

engine ran sweet but had been overheated ,it was like a swiss watch that's why i had it skimmed etc.wish i'd just binned the f00kin thing now

[craigieeb]

So whats your plan of attack?

[magpie]

head off and see if it's got any bent valves ? i've got the other head from the blown engine which looks to only have slight marks on two valves .

i take it i'll need a new h/g and bolts ?

[maggspower]

Don't take it apart Mick, if you have a leakdown test done on it you will be able to tell where your compression leak is.

Basically, air is pumped into the cylinder at TDC via the plug hole. Then you will be able to listen to where it is escaping from, for example, if you hear it at the throttle, the inlet valve is fooked, exhaust.... the exhaust valve fooked, the dipstick tube...... rings or piston fooked, and coolant header..... head gasket or casting fooked.

It will save you time, and it gives a definitive answer as to what part is the problem. If you take the head off and the valves are fine, you have very few ways of then checking the bottom end.

[magpie]

how do i go about this leakdown test, i mean who does it ?

[Neilios]

Use the compression tester modified to be feed from the compressor.

[magpie]

good idea Neil but how do i do that ?

[maggspower]

how do i go about this leakdown test, i mean who does it ?

A good garage should have one.

Use the compression tester modified to be feed from the compressor.

Although, this is an idea. You could cobble something together if you have access to a compressor. The tester will usually have 1 or 2 gauges, from which you can work out how much each cylinder is leaking. I suppose you just need to fine out where it is leaking as you already know its fooked.

So if you could get say 100psi into the cylinder, then you could listen to where the air is escaping from. This must be done at TDC to that piston, so that the valves are closed, and it doesn't shoot the piston back down the bore. So yes if you could use your comp tester fitting without the gauge on it and hook this up to a compressor it would work.

[magpie]

cheers,i'm going to have a crack at this today.i've got Neil's compressor here .

so just take plug 6 out and turn crank until piston reaches top of bore ?

and take the rad cap off ?

[driftwood]

I had similar issues many years ago. To make my own tester I gutted a spark plug and welded on a male airline connector. Turn the engine over by hand till no.6 is at tdc on the compression stroke - valves closed. Remove the oil filler cap, coolant filler cap, manifold inlet rubber boot and dipstick. Screw in the modified spark plug. Connect the airline via a pressure regulator. Slowly increase the air pressure. Listen for air escaping from the oil filler hole, coolant tank, exhaust and throttle body. Air coming from the exhaust and throttle body indicates problems with the valves. Air coming from the oil filler would suggest a problem with the piston/bore. Air leaking through the coolant suggests head and gasket problems. You may need a deep socket to fit over the modified spark plug. Increase the air pressure slowly. You probably won't need much pressure to find the fault. If you have access to an endoscope you could do a visual check.

[maggspower]

cheers,i'm going to have a crack at this today.i've got Neil's compressor here .

so just take plug 6 out and turn crank until piston reaches top of bore ?

and take the rad cap off ?

It must be on the compression stroke, so the valves are closed. Needs to be bang on TDC so it doesn't shoot the piston back down the bore. So where you set TDC yesterday for the pics, then another full turn, this will set 6 on its compression stroke. But you could put a piece of tissue in the plug reccess and wait for it to be blown out, or stick your thumb over the end of the tube waiting for the compression stroke while the engine is being turned, take the other plugs out it'll be easier to turn.

Have the compressor full, then turn it off so it doesn't fire up and you can listen for the leak. You need to listen at the throttle body, if you hear air here, this will mean it is leaking past the inlet valve. Go to the exhaust, if you hear it here it will be leaking past the exhaust valve. Then the dipstick tube, if you hear it rushing air here is some how getting past the piston, bore, or rings. And lastly the header tank, air here and gasket or casting is fooked. It doesn't matter which order you do it in.

Get the engine warm before you start, just run it for 2-3 min.

You just need to find a way to connect your compression tester hose to you compressor line. Run it at about 100psi if its got a regulator.

Good Luck.

[driftwood]

Could stick it in gear to stop the engine turning. Also if air escapes from the oil filler you could have a head gasket fault.

[maggspower]

Could stick it in gear to stop the engine turning. Also if air escapes from the oil filler you could have a head gasket fault.

Yep that would work. And yes you could.

Treat the oil filler and the dipstick tube as the same thing, they both go to the same place