EJ18 - Temporary loss of compression after sitting for a while

[Georg]

Good evening guys,

 

there is a really odd phenomenon on my 91 EJ18 since I own the car and which I can't really explain to myself. As it happened to me again recently I thought may one of you ever witnessed something similar on a Suby engine?

 

When I park the car for longer than a few days or up to couple of weeks and I then try to start the engine the following happens:

 

The engine cranks but does not start. The cranking noise gives the impression as if there is a complete loss of compression on all cylinders as it revolutes in a perfectly even speed. Like with spark plugs removed.

I then just have to crank the engine for reeeaaaaally long (usually I pull the fuel pump fuse to not flood my engine during that) and you then actually hear from the cranking noise how one cylinder after the other is coming back to life. After doing that for maybe 40sec and with the fuse in place again in runs completely fine.

 

When driving the car as a daily it never happens. It then starts perfectly, hydraulic lash adjusters are also not noisy in any way or condition.

 

Vehicle mileage is 340.000km, the issue is present since I own the car (200.000km).

I guess for some reason the valves can not close whilst going through that. But why??

 

 

 

Any of you have a clue?

THX in advance

 

Reg from GER

Georg

 

 

 

[1 Lucky Texan]

maybe several small issues - all working against you.

 

oil may be diluted with fuel - so, it runs off the rings quickly.

 

what weight oil are you using? have you tried a heavier grade or one of the high mileage oils?

 

I suppose, to help prove the problem is the rings, you could pull the spark plugs and find some way to spray oil into each cylinder after it has sat long enough to exhibit the problem. Then see if it behave the same way.

[WoodsWagon]

It could also be fuel leaking into the intake from a failing fuel pressure regulator or a leaking injector. Pull the vac hose off of the regulator and see if it's wet with gas inside.