What should my pressure be? Compression test

[rctempire]

Hello all,
My D-Type engine has been compression tested by myself today.
What should my readings be? I need to know before i start any work, as it isnt listed in the Haynes Manual and i cant find it anywhere.

I am getting these readings:

Gearbox end first
Piston 1 - 40PSI / 3Bar
Piston 2 - 35PSI / 2.5Bar
Piston 3 - 30PSI / 2Bar
Piston 4 - 40PSI / 2 Bar.

When oilded the readings go to 50PSI / 3.5 Bar all around.

I NEED to know what the readings should be, and which ones are low.

Thanks.

Rctempire

 

[mattjk]

D-Type? please forgive me, do you mean diesel?

What CCs year is the engine etc...

If the readings increase on a wet test thats not a good sign though. But you are allowed a certain tolerance

 

[ditz]

dosn't sound like sod all to me surprised it runs
even more so if its a diesel lol

 

[Russ_16v]

my 172 made over 180 psi per cylinder matey as a guide

 

[mattjk]

You sure^ I'm sure they are only 160-165 from factory

 

[mattjk]

dosn't sound like sod all to me surprised it runs
even more so if its a diesel lol

Indeed Its very low but need more info really to be able to answer.

 

[Beef-Mc]

Petrol engine IIRC.

 

[davebem]

I take its the D7F (1.2 8V) engine?? Renault dont specify the correct readings, however if the readings go up after adding oil there is a problem somewhere? Piston rings or head gasket?

 

[ditz]

if they increase when oiled its rings
if they dont then its headgasket/valves

 

[mattjk]

Leakdown test for the win homos

Edit: someone told me that its normal for pistons 1 and 4 to be down or up on pressure on the frenchies I can't remember which way unfortunately. The main thing to check is how much oil it drinks!

 

[AlexS]

I believe its the 1.2 8v energy engine (petrol).
Is it drinking oil mate? Did you not just get it rolling roaded at 65hp, seems quite strong.

 

[davebem]

65hp is good for the D7F, they normally make about 58hp.

 

[ashy_gtt]

Don't know the setup on that engine but if you are taking the readings and the plenum / inlet manifold is still attached you need to test it with the throttle fully open!

If those readings were taken with the throttle open then they are far too low.

 

[mattjk]

Don't know the setup on that engine but if you are taking the readings and the plenum / inlet manifold is still attached you need to test it with the throttle fully open!

If those readings were taken with the throttle open then they are far too low.

I bet your right!

Need to do the tests at WOT

All makes sense now!

 

[vts_saxo]

Er.....if those readings are right its f ucked!

 

[rctempire]

D-Type? please forgive me, do you mean diesel?

What CCs year is the engine etc...

If the readings increase on a wet test thats not a good sign though. But you are allowed a certain tolerance

D-Type. Petrol Engine. 1.2L 8V 60bhp.

I believe its the 1.2 8v energy engine (petrol).
Is it drinking oil mate? Did you not just get it rolling roaded at 65hp, seems quite strong.

Yeh got 65 BHP at the RR two weeks ago

Don't know the setup on that engine but if you are taking the readings and the plenum / inlet manifold is still attached you need to test it with the throttle fully open!

If those readings were taken with the throttle open then they are far too low.

.
Engine setup is FULLY standard, nothing is changed.
Im going to double check the readings tomorrow. Most likely the test was not done with the WOT as per said.


What is the correct procedure on doing the Compression test then? As far as im aware, the Haynes manual was followed. I personally did not do the tests, however i will be doing them tomorrow.

 

[mattjk]

I bet its because it wasnt @ WOT, let us know how it goes this time. Sounds like a healthy engine to me

 

[rctempire]

Does anyone know what the pressure should be within the 1.2l 8V Diet(D-Type) Engine?

 

[mattjk]

How much oil does it use?

 

[Ali]

Does anyone know what the pressure should be within the 1.2l 8V Diet(D-Type) Engine?

Spk to kevin @ falkland he'll be able to tell you.

 

[rctempire]

How much oil does it use?

The usual renault amount. Nothing amazing, but the oil does decrease, however i normally change the oil before it goes empty. So realistically i change oil every 7-9 Thousand. Engine does burn oil however, but i knew this anyway, both engines ive had has done this.

 

[rctempire]

Update guys, had the head off the car, the gasket had indeed cracked and a pit had developed on the head.

Off to get it skimmed and pressure checked tomorrow. Hopefully ill be rolling again by monday.

 

[rctempire]

Update 2 - Got head back yesterday, built engine backup yesterday and today.
Head looks like it had been skimmed before the guy said, also looks like the engine ive got had a problem previously. The piston had a mark from where the valve hit it also.

Hopefully the car should be rolling for tonight.
At last.

 

[rctempire]

Update 3 - Head on, looked good, then problems.

Cylinders 3 and 4 wouldnt fire. Took rockercover off, adjusted tapets and cylinder 3 fired. Cylinder 4 still has a problem with it.

Looks like head will come off again and ill be doing the valves.

 

[mattjk]

Not being too lucky here sorry to hear its still broken