I've just finished rebuilding all chains / tensioners and head gaskets on my 4.0 NA XK8 vert. The cams and other bits in the heads have been lubricated with gear oil as recommended in the JLR manual. Whilst the car was laid up, the fuel pump failed, but has now been replaced, so there's nothing to stop it from starting now is there?

The engine hasn't been run in 18 months (new front subframe, suspension bushes and rusty floors / chassis rails done too), so I'm thinking there isn't much oil around the bottom end. Should I just start it up, or should I disconnect the fuel pump, pull the spark plugs back out, spin it over until it's got oil pressure, put everything back and then start it?

I've heard some say that it should just be started, as that will get oil round quickest, and then others recommend the 'prime' process.

Any opinions?

 

I always disable the fuel injectors and crank in short bursts until there ia oil pressure. Disconnecting the fuel pump is good unless you have had the ignition on recently and have some pressure in the fuel line.

 

I just finished my repair a few weeks ago. I replaced a piston and bearings and a head rebuild. I also lubed everything up when installing all parts.

Even with this I primed the motor before starting. I don't know if it was necessary but I like to see the oil pressure gague show pressure before I start the engine. I feel that if for any reason you don't get oil pressure you will do less damage by cranking it with the starter than the engine running at 700+ rpm.

I had the plugs out so the engine was cranking freely and removed the fuse for the fuel pump.

Good luck on your restert. Knowing you you'll be posting a video of the restart and we can all hear you Jag come back to life. But if it is at 4× you'll be at 2800rpm.

 

OK, decision made, I'm going the BobRoy route. It'll take a bit longer, but I really don't want to risk having to rebuild anything else before I get a chance to drive this. Apart from driving this XK8 onto the trailer at idle, I have yet to drive any Jaguar...

Video to follow... probably next week.

 

I agree with Bob also. Pull plugs and fuel pump relay, add battery charger and crank away a few times until you see oil pressure. That's the way I've done all my customers cars when major engine repair was performed.

 

Me too. I can't think of any downside to doing it this way other than the extra effort..
..which is insignificant compared to a damaged bearing, etc.

M