Finally got the beast running, but its poorly :(

[poboyle]

Well, got the golf gti mk2 me and my dad have been solidly working on this week working. Gave it a test drive today and its pretty damn fast! However, there are a couple of problems that i was wondering if you guys could help me out with. The tappets are making noise - we changed the oil filter, flushed it and put new oil in and the noise quietened, but then got noisier again. When i put my foor down, the oil light on the dash came on and a buzzing noise also from the dash (wasn't there before when just the oil light was on). Also, after a few mins of driving, when driving and the revs drop (when slowing down to stop or 3 point turn or something), the car stalls.
We have pretty much reconditioned the head of the engine and don't really know whats going on now. The engine idle speed was all over the place and now its pretty stable, but when you rev the engine, the speed drops below engine idle speed nearly to stalling and then back up again (to about 800 rpm) Can anyone help me please??
Thanks, Peter

[waynne]

Sounds like a dodgy sensor to me. The tappetts will rattle until they get coated in gunk again - some slick 50 or X1 superlube will help keep the rattle down.

I would unplug and replug everything in again including air feed pipes just to be on the safe side. The buzzing noise implies a short across a relay or switch. Keep revs to below 3000 for the first 300 miles while you are bedding things in - I'm assuming the bottom end and engine below the head gasket are not touched.

There could be an oil pressure issue as well - you really should keep an eye on the oil pressure with a gauge.

[poboyle]

The tappets noise did reduce when we put the new oil in but then it got louder, possibly indicating that the oil isn't circulating properly. The buzzing isn't always there, just when i put my foot down a fair bit usually. How am i ever going to keep revs below 3000 for 300 miles when i'm finally allowed to drive this thing on my 21st birthday?
and yes you're right, the bottom end of the engine hasn't been touched.

[fingers]

I'm sure I've asked this before but whats the mileage on the engine?

[poboyle]

It's done 159000 miles (cheap bargain, i couldn't resist!)