Leak Down Test

[TonyBrooks]

The engine is a 4 cylinder 1647 cc engine from a Renault 16 TS as fitted to an Alpine Renault A310.

Over the past week I have noticed the occasional large puffs of white smoke coming from the exhaust, always when accelerating hard. This suggests to me a failing head gasket.

There is no water in the oil (as far as I can see) and no bubbles in the expansion tank and the level has only gone done marginally.

Carried out an engine compression test and 3 cylinders are at 170 and one is at 165 so happy with that.

Just done a leak down test - first use of a birthday present from several years ago!

The instructions say use on a warm engine and put pressure of 65 psi into the cylinder. Whilst I used it on a cold engine, if I put 65 psi into it, the leak gauge goes all the way round the dial. However if I limit the pressure to 20 psi then I see a constant 20% leak on all cylinders.

So may I seek opinions on the technique I have used and perhaps any other suggestions on the white smoke (it is definetly not blue)

Thanks

[ChrisPackit]

Isn't there any adjuster knob under the gauge so you can dial down the pressure? I have found leak down testers are good, but work better when the manifolds are off so you can get a better idea of whether its intake or exhaust thats causing the issue.

Also, didnt the A310 come with a V6 in it? I have an Alpine GTA turbo, so keen to see how you get on!

[TooMany2cvs]

ChrisPackit said:

Also, didnt the A310 come with a V6 in it?

There were four-pot 310s as well as sixes.

Not sure "white smoke on acceleration = HG". You sure it's white, not pale blue oil?

[Ardennes92]

Water in the fuel, could be steam/vaporisation?

[9xxNick]

Brake fluid entering the combustion chamber causes very white and quite dense smoke. If it is the culprit is the brake servo.

[TonyBrooks]

Thanks for the various suggestions. I have no Brake servo so I don't think brake fluid is the culprit but good thought. Whilst I have a new head gasket ready to go on, I am reluctant to replace just yet. Other competitors on my event at the weekend all said it was white smoke and strangely, when I spilt a cylinder head on another car some years ago, I had a similar show of smoke. I think I will give it some further hard running over the next few days and reevaluate.

[838HNK]

I had a Ford 302 with a very small crack in one head between the water jacket and the exhaust port. I had good compression on all pots but when the engine got hot had "white smoke" .... but I also had coolant loss.

If you do go for the head gasket maybe a crack test would be worth it ... ?