Oil pressure light and no start 97 b4 sedan

So to start things Off. A few weeks ago I bought a 97 Passat. Things seemed pretty good a little bit of wear and tear 260000 miles. But didn't seem to have any major issues. Drove the car 1700 miles and it did great 43 miles to the gallon 90 miles an hour the whole 9 yd. I get back and the engine light is coming on intermittently throughout the trip. So I go to investigate and find that cylinder 4 has a Bolt cross threded into it and the glow plug harness isn't even plugged in so I ran all the way out there on 3 cylinders with no major Issues. So I go to fix the Glow plug andThat's when everything started to go downhill fix the glow plug with a Heli coil. So now the oil pressure sender sensor is going off and I can't start the car I've read a bunch of stuff that everybody's posted on here about putting up pressure gauge on the engine as well as checking the Sensor. My question is is where should I start.

I think I’m following....

Cylinder 4 was missing a GP and someone installed a bolt in the hole and cross threaded it?

CEL is coming on intermittently.

You installed a helicoil in the fubared GP hole, installed a GP and now the car won’t start? Nothing else was touched?

I’d get your car scanned. I doubt these cars have any low pressure safeties built in. I don’t see the CEL coming on because of a missing GP.... something else is going on.

When you turn the key on, do the CEL and GP lights come on momentarily?

-Todd

Since posting the original thread I have purchased a low pressure sender on the block and I have a high pressure one on order along with a mechanical gauge to install. I have since also replaced the oil breather tube/hose and the antifreeze/coolant connector. My mechanic came over and helped me do a little trouble shooting, battery is toasted, the glow plug coolant relay is fried and now we have no fuel pressure. The cell lights come on and then go off normally and then once I start to crank the check engine light and oil pressure light come on. What would cause all this to go wrong all at once? Could it be from neglagence of the last owner?

Normal for the CEL and oil pressure light to be on during cranking (as a bulb test, plus there's not enough oil pressure at cranking RPM, so the oil light will eventually come on if the engine doesn't start).

Perhaps a bit more info about what you mean by "no fuel pressure" would be helpful. I ask because there's no in-tank pump, so no fuel pressure in the system externally other than at the injectors themselves, which you can confirm by loosening the nut on the top of each injector a turn or so to see if fuel comes out while cranking. The rest of the system is under suction, to draw fuel from the tank and thru the fuel filter.

Pulled cap off at fuel Filter and no pressure at fuel filter. I will pull and injector cap and see if there's any pressure at injectors, Thanks for the info. What would be the reason of not having fuel at the fuel filter?

Manesac54 said:

Pulled cap off at fuel Filter and no pressure at fuel filter. I will pull and injector cap and see if there's any pressure at injectors, Thanks for the info. What would be the reason of not having fuel at the fuel filter?

Click to expand...

You won't be able to see fuel under the fuel tee, since that's the drain back and there's a metal lip about half an inch down. And as above there's no pressure filling the fuel filter, only vacuum.

If in fact you cranked the engine with the fuel filter opened you'll have introduced air into the system which will mean no fuel at the injectors either.

To purge you'll want to:

- refill the fuel filter with clean diesel thru the hole you were peering in
- put the top tee fitting back on the fuel filter
- crack the four top injector nuts a turn or so
- have a rag and fire extinguisher standing by
- crank the engine in 20 second bursts (to allow the starter to cool) until you get fuel dribbling out the top of the injector nuts
- tighten the injector nuts and mop up any spilled fuel

Well crap, ok I will be doing that later today. Would the relay 109 going out cause it to stop having vacuum and fuel or a faulty battery.

On another note the collant/preheat relay for the glowplugs is compleatly melted, obviously I need a new one. Will I be able to repressurize the fuel system without it?

Also found a vacuum tub just laying in the engine bay attached to nothing and I'm not sure if it's super important. Has a check valve and is hard plastic,one rubber grommet on one end and a nipple thing on the other, any ideas?

'97 b4 passat
Casey

That is for the coolant glow plugs and it's not monitored or needed, so don't worry about it right now.

Ok so injectors have been bled, a mechanical oil gateway installed, both oil senders replaced, fount the issue as to not starting(the fuel shutoff valve was stuck closed ).
So now to the issue of the oil pressure light and buzzer. Started with jumper on the fuel shutoff switch to allow fuel to flow free. All lights came on and went off per normal. Idle oil pressure was 40 ish psi. At 2200rpm gauge was reading 75 ish psi this can't be with in normal range and if so how come the oil light and buzzer sound?
Casey
'97 B4 Passat

75 psi with the engine cold is probably OK actually. It will drop down fairly quickly as the engine warms up and the oil thins.

In terms of the buzzer... the older VWs used a "dynamic oil pressure warning system" that used two sensors... one normally-open and one normally-closed, with different PSI ratings on each.

Can't remember if the early TDI Passats had this too... but worth checking to see if there is an oil pressure sensor by the oil filter manifold and another on the driver's side of the head.

If so... most likely the wrong sensor is in the wrong spot.

More info on the dual-sensor system here (but start by seeing if this even applies to your model year by checking for two oil pressure senders!):

http://vincewaldon.com/index.php?option=com_content&task=view&id=40&Itemid=28

Thank you guys for the info and link. Turns out the connection in the main housing on the block had a few bad pins so long story short traces everything back tested and double checked then cleaned cut and reconnected. Yay running properly now on all 4 cylinders.

One light still coming on but I think it's due to not having the coolant gp relay.

Casey
'97 B4 passat

Nope, the coolant glow plug relay is not monitored.