2.1 DJ won't fire up after head rebuilds
Posted: 09 Jul 2023, 15:07
Hello, really hope someone can offer some guidance here.
1992 2.1 DJ automatic
*Full history here in case anything is relevant*
Buddy has been a really good runner for us since we bought around 5 years ago. I maintain it myself. Regular oil changes and anything else that's needed. Fuel injectors were professionally refurbished 2 years ago. If left for a while there would be some tapping on cold start but this always cleared once oil got hot.
Everything was fine when parked up last September, except I noticed coolant dripping from RH cylinder head seal. Decided to wait until weather improved before tackling this.
Started work back in April. The battery was flat so I couldn't start it before doing the work but I assumed it would be ok. Took photos of the HT lead order and injector wiring. Ended up taking off both cylinder heads as the LH one showed evidence of a leak as well.
The heads looked really good. Typical crack between the valve seats. As a precaution I sent them to my engineer and he cleaned them, stripped, refaced the valves and checked the guide wear. All checked out good. I noticed that two of the valve adjusting screws had worn tips so I replaced those. The tappets were left in the block but were solid when I poked them with a pushrod. I also checked each pushrod for flatness by rolling on a granite worktop.
Put it all back together again using original VW tech manual. All new gaskets. Jacket seals coated with Dirko grey paste. Head nuts coated with Hylomar blue. I was very careful to ensure each pushrod was correctly seated. I loosened off each valve adjuster. In the process of turning the engine by hand to check each adjuster the tappets all went soft. So I adjusted them until each was just touching the valve then +1.5 turns.
Unfortunately I messed up and didn't torque the two centre nuts under the rocker shaft in RH head. When I filled up with coolant it was dribbling out of the sump drain. (Coolant was getting into the rocker area and dribbling down the pushrod tubes) Luckily I noticed this, cleaned up the nuts and sealed then tightened them. No coolant leak now and did a pressure test too. I'll run the engine until hot then change the oil for clean stuff.
Now, trying to fire it up and I'm not having any luck. First it was not cranking at all. The starter solenoid wasn't clicking so I removed it, put a tiny bit of grease on the brass sleeve inside and refitted. I also cut off the old 6mm crimp from the wire and fitted a new one. Starter was now turning but very slowly.
Fitted new battery, 70Ah 640CCA . I also removed the grounding strap by the gearbox mount and cleaned everything. I moved the connection on the negative lead from the battery to a stud under the seat as the old screw and captive nut in the wheel arch was very rusty. Engine now turns over much better, probably as good as you can get for one of these.
So what happens now is that it just cranks but won't fire up. Everything is as it was before, comparing the photos I took before disassembly. If I play arrive with the injector or HT lead order then I can sometimes get one cylinder to fire once but that's it, will just keep cranking.
I've checked the following:
Compression - 210psi cyl 1, 215psi cyl 2, 190psi cyl 3, 190psi cyl 4. I forgot to open the throttle but the values are nice and high. I've read that around 190psi should be expected.
Injectors - removed and held them over a plastic pot. All are pulsing with conical jets during cranking.
Spark - removed all plugs (looked ok but smelt of fuel). Fitted HT leads and lay the ends on the block. When cranking I can see sparks on all of them. So hopefully that rules out the hall sender, TCI module, coil, leads and plugs?
Order - Set cyl 1 to TDC with the rotor arm pointing at the corresponding HT lead. If I turn the engine by hand I can see the exhaust valve starts compressing so I know that cyl 1 was on the firing stroke. So hopefully that proves the dizzy is not 180 out of phase. HT leads are set the the correct firing order 1-4-3-2 going clockwise.
So I think I have ruled out the obvious things that could stop an engine from firing. It feels like something is out of phase but I believe it's all as per the book. I'm cranking until the battery gets low, then recharge. I can't bump start because it's an auto. This was a running engine before I started work so it's something I've done since the rebuild. Some other things I'm thinking:
I didn't start the engine before commencing the work, so I can't guarantee the fault occurred in the time it was laid up since last year, before I started the rebuild.
Could the plugs be fouled? They spark when removed and tested but could the fuel be wetting them? I haven't tried new plugs.
I wondered if the valve adjustment was wrong. I've now wound the adjuster screws back 1.5 turns to remove all preload, still doesn't start.
Have I bent a pushrod from not seating it correctly?
Has the fuel gone bad?
Has the ignition advance suddenly gone bad? I hadn't touched the dizzy. All vacuum lines are connected.
I'm going mad here and will probably miss camping this year. So any guidance or advise is appreciated!
1992 2.1 DJ automatic
*Full history here in case anything is relevant*
Buddy has been a really good runner for us since we bought around 5 years ago. I maintain it myself. Regular oil changes and anything else that's needed. Fuel injectors were professionally refurbished 2 years ago. If left for a while there would be some tapping on cold start but this always cleared once oil got hot.
Everything was fine when parked up last September, except I noticed coolant dripping from RH cylinder head seal. Decided to wait until weather improved before tackling this.
Started work back in April. The battery was flat so I couldn't start it before doing the work but I assumed it would be ok. Took photos of the HT lead order and injector wiring. Ended up taking off both cylinder heads as the LH one showed evidence of a leak as well.
The heads looked really good. Typical crack between the valve seats. As a precaution I sent them to my engineer and he cleaned them, stripped, refaced the valves and checked the guide wear. All checked out good. I noticed that two of the valve adjusting screws had worn tips so I replaced those. The tappets were left in the block but were solid when I poked them with a pushrod. I also checked each pushrod for flatness by rolling on a granite worktop.
Put it all back together again using original VW tech manual. All new gaskets. Jacket seals coated with Dirko grey paste. Head nuts coated with Hylomar blue. I was very careful to ensure each pushrod was correctly seated. I loosened off each valve adjuster. In the process of turning the engine by hand to check each adjuster the tappets all went soft. So I adjusted them until each was just touching the valve then +1.5 turns.
Unfortunately I messed up and didn't torque the two centre nuts under the rocker shaft in RH head. When I filled up with coolant it was dribbling out of the sump drain. (Coolant was getting into the rocker area and dribbling down the pushrod tubes) Luckily I noticed this, cleaned up the nuts and sealed then tightened them. No coolant leak now and did a pressure test too. I'll run the engine until hot then change the oil for clean stuff.
Now, trying to fire it up and I'm not having any luck. First it was not cranking at all. The starter solenoid wasn't clicking so I removed it, put a tiny bit of grease on the brass sleeve inside and refitted. I also cut off the old 6mm crimp from the wire and fitted a new one. Starter was now turning but very slowly.
Fitted new battery, 70Ah 640CCA . I also removed the grounding strap by the gearbox mount and cleaned everything. I moved the connection on the negative lead from the battery to a stud under the seat as the old screw and captive nut in the wheel arch was very rusty. Engine now turns over much better, probably as good as you can get for one of these.
So what happens now is that it just cranks but won't fire up. Everything is as it was before, comparing the photos I took before disassembly. If I play arrive with the injector or HT lead order then I can sometimes get one cylinder to fire once but that's it, will just keep cranking.
I've checked the following:
Compression - 210psi cyl 1, 215psi cyl 2, 190psi cyl 3, 190psi cyl 4. I forgot to open the throttle but the values are nice and high. I've read that around 190psi should be expected.
Injectors - removed and held them over a plastic pot. All are pulsing with conical jets during cranking.
Spark - removed all plugs (looked ok but smelt of fuel). Fitted HT leads and lay the ends on the block. When cranking I can see sparks on all of them. So hopefully that rules out the hall sender, TCI module, coil, leads and plugs?
Order - Set cyl 1 to TDC with the rotor arm pointing at the corresponding HT lead. If I turn the engine by hand I can see the exhaust valve starts compressing so I know that cyl 1 was on the firing stroke. So hopefully that proves the dizzy is not 180 out of phase. HT leads are set the the correct firing order 1-4-3-2 going clockwise.
So I think I have ruled out the obvious things that could stop an engine from firing. It feels like something is out of phase but I believe it's all as per the book. I'm cranking until the battery gets low, then recharge. I can't bump start because it's an auto. This was a running engine before I started work so it's something I've done since the rebuild. Some other things I'm thinking:
I didn't start the engine before commencing the work, so I can't guarantee the fault occurred in the time it was laid up since last year, before I started the rebuild.
Could the plugs be fouled? They spark when removed and tested but could the fuel be wetting them? I haven't tried new plugs.
I wondered if the valve adjustment was wrong. I've now wound the adjuster screws back 1.5 turns to remove all preload, still doesn't start.
Have I bent a pushrod from not seating it correctly?
Has the fuel gone bad?
Has the ignition advance suddenly gone bad? I hadn't touched the dizzy. All vacuum lines are connected.
I'm going mad here and will probably miss camping this year. So any guidance or advise is appreciated!
).
