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Discussion Starter · #1 ·
‘97 D1 4.0, GEMS, 175k.

Briefly: New head gaskets. Have fuel, starter’s good, have spark. No start. Pop on first crank, then nothing. Did not touch timing case.

Ran fine, but had overheating issues when pointed uphill and was leaking all over, so did the head gaskets. Heads were a bit warped, but not too much. Clear signs of coolant leaks on old gaskets. Had heads machined to get them flat; don’t know if they’d been done before. Got it all back together, but the injectors weren’t sealing. So pulled the intake again and replaced with new Mustang yellow injectors.

Still no start. Starter motor goes hard. There’s pressure in the fuel rail. Spark light tester shows spark (new Champion plugs). But all I get is a small bang/pop on the first crank and nothing else. There’s a slight bunt smell afterwards from the motor. I didn’t remove the timing case. I did rotate the crankshaft with the heads off to clean the piston heads, but that shouldn’t matter on a pushrod, right?

Button on the passenger firewall is depressed. Fuses for each firing system are good. I haven’t swapped the ignition module because I’m not sure where it is (and my laptop with the Rave manual downloaded is offsite). The wiring harness was a mess (especially everything that hung below the valve covers), so I cleaned it up a lot with brake cleaner. Battery is weak at the moment, putting my 500 crank amp jump pack on it doesn’t help.

I have not done a compression test. Planning to tomorrow.

Replaced a number of accessories and components at the same time (steering box, cores-out radiator flush, power and ground cables to starter and chassis, solenoid ground, ac compressor, thermostat, all rubber vacuum lines, heater core, heck even fenders, the hood, headlights, rekeyed the ignition cylinder - too much). I also cleaned the engine bay, engine, and undercarriage throughly when the heads were off. It was all super gross. I wrapped the top of the block with a tarp to keep water out and removed any remaining electrical components from the engine bay, but I don’t know if water might’ve damaged something.

Need this thing running - new job and new child. This Disco needs to get in the rotation.


Something to consider: I’ve got a ‘96 D1 GEMS that runs just fine (more or less). So I can yank parts off that and plug them into the ‘97 for troubleshooting.


Questions:
Could the crank or cam sensors be bad but the ECU still allow spark?
What should I pull off the running truck to try on this one?
I don’t know if these heads had been skimmed before - how much material would need to be taken off before the pistons slap the valves?
What am I doing wrong?!?


Thoughts and suggestions are much appreciated.

Cheers
 

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2003 Discovery 2 SE7
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My only thought is that your injectors aren’t pulsing properly. Try swapping in some new/different injectors. Other than that, just go over the wires and everything and just make sure it’s all plugged in and good to go. Maybe you forgot a ground or something - it’s worth just looking it over for stupid oversights.
 

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Discussion Starter · #3 ·
Was hoping it was the injectors… compression test said otherwise.

Sequence:
(Cylinder - psi)

1 - 120
3 - 30
5 - 95
7 - 95

2 - 120
4 - 120
6 - 0-15
8 - 115

So both banks are affected. What is that about? Went out to get a new test gauge just to be sure. Have done this job on a 4.0 before just fine. But man, something is afoul today.

I put a precision straight edge on the block before assembling. No gaps. I’ve used this machine shop before with success. I put a wrench on the exposed head bolts and they’re all just as torqued as they outta be. I can see and feel that the gaskets are actually in place (in the event I somehow overlooked laying down gaskets on BOTH sides before installing heads). What on earth is this about…?

Anything else you all suggest before tearing the whole lot down again? I’ll pop the passenger valve cover off to see if the rods are trashed next I suppose…


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Discussion Starter · #4 ·
My only thought is that your injectors aren’t pulsing properly. Try swapping in some new/different injectors. Other than that, just go over the wires and everything and just make sure it’s all plugged in and good to go. Maybe you forgot a ground or something - it’s worth just looking it over for stupid oversights.
Was sure hoping that to be the case. Was planning on moving quickly on to swapping injectors for the stock units after ruling out compression. BUT NAY!!!

Pulled a valve cover and pushrods are all a-okay. (Well, a couple of them are off by a bit - when rolling down a 20” table, they run maybe 4 degrees astray. But like, is that “bent”?)

Threw a socket on exposed head bolts and they’re damned tight. Thinking maybe the cam/crank timing and valve position is the matter… but again, thought the nature of a pushrod architecture would force valves to be in step…


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I would not worry too much about the compression test just yet as the lifters would may not have had enough to pump themselves up yet. How much did they take off the heads? There is a machined block at the back and front of each head. if you measure the thickness of the those blocks and compare them to the Standard measurement, you will know how much has been taken off over their life. If a fair bit has been removed it may be affecting the settings on the rockers and you may have to fit spacers under the rocker assembly to get them to operate properly.
 

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Crankshaft position sensor is the only thing I can think of offhand that might cause that. "I also cleaned the engine bay, engine, and undercarriage throughly when the heads were off ... " suggests you might have disturbed wiring or pushed water into a connection underneath, which is where that sensor is located. I'd start there.
 
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