‘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

 

Bump.

I am just getting started on my journey to understand the rover v8.

I am glad you reached out. Someone on here will be able to help you. There’s probably someone close to you.

I have a feeling the members are going to tell you that rotating the crank a certain direction might be an issue. That is solely based off of reading previous posts. But what do I know. You mentioned that you didn’t mess with the timing chain so Idk.

I would carbon copy your posts to the D2 page. It’s essentially the same engine… there are more people on there and might be able to help.

Edit:

Since you replaced so many components and did some much wire unplugging. The folks here are also going to advise you to go through and start checking every plug. Make sure you didn’t pinch them down and clip a wire. Also grounds.

Edit:

Are all of your spark plugs and wires in the correct orientation?

 

You seem extremely savvy , but I wanted to verify that you researched the mustang injectors? Are they compatible with the fuel system you have? Just a brief search led me to see that a lot of members just use rebuilt injectors and there may be some compatibility issues with the Fuel delivery systems… for which I don’t off hand know the differences.

 

EDIT: Good Lawd! Just realize I didn’t rotate the crank between cylinder tests. Man. Gotta stop doing this stuff in the middle of the night…

Hells bells!

Compression test complete : super low on two cylinders; no compression on another.

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…

 

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”?)

@WildPackofFamilyDogs

Thanks for those thoughts. Quickly: double/triple/quadruple(?) checked connecting keys, loose wiring, plug and coil connections. And I have used this Mustang “upgrade” on another 4.0 with success. But sure damn hoping it was the injectors. Compression matter has me flummoxed.

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…

 

A quick search led people to try and rotate the crank pulley ever so slightly to feel resistance or binding.

do you remember which direction you rotated it?

 

So, you checked spark. Then, I would check a fuel injector circuit to see pulses on a voltmeter when you crank. If no pulses, then maybe a bad crank position or other sensor. I use Mustang injectors (4 hole, 19#/hr) in my truck.

Maybe a spoonful of oil in the low compression cylinders, then test compression again. They need oil to seal completely and can get washed out with gasoline. That low compression is troubling. Then cover with the basics: Fuel, Air, Spark, and timing. You can do this!

 

I just had this same issue. You’re crank position sensor wiring is either lose or compromised.

in my case, when moving the wires all around, you end up pulling on it and mine unclipped from the sensor.

it’s a cheap part of needs to be replaced and about 45min job to get it hooked back up.

on drivers side, pull off exhaust manifold (afyer timing the air intake), near the rear if he engine is a little plastic covering, you’ll need to take this off to access the sensor. Once off, make sure the sensor plug is tight and try turning over again. It should fire up right away. Turn off and reassemble.

I wrote about this last month or so. Wrote up for to take off/access the sensor too.

https://discoweb.org/index.php?threa...-on-d1.100070/

 

You guys are all way more experience than I so I am quietly lurking taking it all in, however for anyone else lurking like me I wanted to post some information about the rover V8’s in case anyone other poor souls are reviewing and assessing how to do the job you guys are describing.

This information is all scattered by many different forms and pieces across the internet. This article and information captures a lot of helpful information for anyone thinking to do a head gasket job.

So much so that it is located in the D2 forums under the Stickies Tech section listed as must reads, how to’s and guides. This is listed as a must read before attempting to do this. I have been reviewing it and cross referencing this in preparation to do thine own head gaskets one day.

RPi Engineering - V8 Engines