SA 2.5 Microbus - High rev problem when idling - blew gasket

[MayaTheBee]

Scenario: Van starts fine, idles fine <1000rpm, drives fine. Temp gauge rises to about a quarter of the way (below the red LED). Drive for about 15 minutes (normal cruising speed between 60 & 80kph), with no problem going through the gears.
Problem: Stopping at an intersection, put gear in neutral and revs go up to 3000rpm, sometimes 3500rpm. No problem selecting gears, clutch working fine, no grinding etc. Only issue is the extremely high revs.
What I've checked: Coolant level is fine, oil is fine. I can rev it over 4000rpm and it will settle back to 1000rpm (in garage).

What can be the problem, what do I check?

[72BUG]

Sounds like the carb may be ready for a refurb. Assuming it's a petrol van as you've left us guessing on that one.

[MayaTheBee]

Sorry , it's a 92 Microbus (5-cylinder) 2.5i fuel injected petrol engine...

[72BUG]

Ah. In that case we can probably rule out the carb.

[ghost123uk]

it's a 92 Microbus (5-cylinder) 2.5i fuel injected petrol engine...

Nice

One of our resident 5 pot experts will (likely) be along soon with helpful advice.

[MayaTheBee]

Ah. In that case we can probably rule out the carb.

One less thing to worry about

[jason k]

Sounds like a temperature sensor.

[MayaTheBee]

Sounds like a temperature sensor.

YES! And apparently worse... much worse. Today the engine overheated, ruptured a hose. I then decided to apply my mind [or least McGyver's mind], all I had was insulation, sellotape and a scissors. Then I drove for about 5 km's with the temp gauge at the hottest, now no compression whatsoever.

Being towed to mechanic to assess how stupid I was...

[MayaTheBee]

So far it's clear I blew the head gasket. Will be stripping over the weekend to assess extent of the damage I caused.

[Wychall]

Sorry to hear this, mate.

Also sorry to have missed your thread until now. I had scanned down the list of new posts and passed over your thread as I know diddly-squat about WBX, diesel or air-cooled engines. Had I known it was Audi 5 pot I would have been straight in there. Might be worth including SA in any future thread titles to ensure you wake up the right people.

Keep us informed as to how things go (I assume you are still running K-Jet injection?).

[MayaTheBee]

Sorry to hear this, mate.

...(I assume you are still running K-Jet injection?).

I've come across a pdf for Bosch K-Jet Technical Instruction - if you're interested PM me and I'll mail it to you, it's about 1MB

[MayaTheBee]

So far it's clear I blew the head gasket. Will be stripping over the weekend to assess extent of the damage I caused.

Besides the gasket, cylinder 5 is worst off. Head will be sent to engineers then pressure test to check if block is cracked - already sounding expensive

[MayaTheBee]

So far so good... or so I thought

Valves and guides to be replaced, cylinderhead to be gas-flowed and then attend to cracked manifold (hoping to find a good 2nd hand one), welding ain't gonna work as it will crack again... So the Rustoleum has been put on the bottom shelf at the back in cupboard for now

I owe, I owe, it's off to work I go!

[Wychall]

Sounding expensive!

Are the bores and pistons ok or do they need attention as well?

[MayaTheBee]

Sounding expensive!

Are the bores and pistons ok or do they need attention as well?

Fortunately they're ok - but still expensive. I was always prepared to fork out some cash to attend to the van... but over time - not so soon after purchase! Anyway, we'll see what the weekend holds