Car is a 1996 Disco I. Has around 130k miles on the clock. Being an avid hunter and just in general enjoying the outdoors, I have to get this truck back into perfect running order. The reason is because I have to get lots of gear into places that a regular car cannot go.

My current problem is this, and has yet to be answered. I have talked to mike on the phone awhile back and tried everything he said and it didn't work. And I don't blame mike at all, its hard to diagnose on the phone lol.

The car has a bad constant misfire on the number 5 and 7 cylinder. I have changed the injectors (they were bad anyway and leaking), new spark plugs, 8mm wires. That changed nothing. It has been stumbling 50-55mph like it doesn't want to go and then it evens out after you get above 50. It also had a barely noticeable knock under load for awhile. Lately it has started knocking constantly. So I took it to a mechanic who actually works on Rovers some. He said it was a lower or upper lifter (never heard of these, I'm guessing with others help, he was talking about a lower rocker arm and push rod?) and these lifter's had become bent. Following this logic, this would explain my misfire because one of the valves would be constantly open allowing a misfire.

Can anybody else confirm or deny this theory I have? Its pretty much the only theory I have that can tie all the problems together. I have not found any metal flakes, or shavings in the oil yet, so I figured it wasn't a spun bearing.

I plan on seafoaming the car as a last ditch effort this weekend before I pull the engine apart. Can anybody point me to any other help besides the Rave manual, which I have and have been looking over?

Also can anybody confirm or bring to light any other ideas on this misfire?


Thanks,
Brian

 

https://landroverforums.com/forum/sh...ad.php?t=26263

Replace your rocker arms, rockers and lifters.
And while you have the valve covers off clean everything up as best you can.
Then put it back together and change the oil, then change it again after 500 miles.

 

He had a valve clatter, but what your saying is that you think thats the cause of the problem spike?

 

It very well could be bad rod bearings, or it could be a bent lifter, but if thats the case why did it bend?
They dont just bend on their own, something was causing it to happen.
You can remove the oil pan and replace the rod bearings pretty easily.
Same with the lifters and rocker arms and shafts.
No it wont be a total rebuild because you are not replacing the piston rings but so what?
Have you done a compression test?
That will for sure tell you if it is a stuck valve.
But backfiring is a sure sign of either timing being way off or a stuck valve.
You have a '96 so you have electronic ignition, your knock sensor could be bad but that usually throw a code. (a knock sensor adjust ignition timing automatically by listening for spark knock)
If you had a pre '96 I would say to start with the ignition timing.
Do a compression test, then pull your valve covers and look for engine sludge, you may just have a stuck valve spring.

 

To answer why it could have bent, the car was driven hard before I drove it. The person who owned it gunned it because of an anger issue (is what he told me). The car has not run right since then, and has gotten progressively worse and worse. I baby the poop out of her too on top of that.

Compression in number 5 and number 7 both read 0. I thought I did it wrong, I have never gotten a number that low.

 

Then I would say your rod bearings are good and that you have a stick valve or lifter.
Just remove the valve covers and have a look see.

 

Another question, will I need to replaced the valve cover gaskets, or is it more advisable to use something like the right stuff instead.

 

I would replace the gaskets with new ones, they are cheap and will be needed.
But that is the least of your worries right now.

 

Just thought of this, 5 & 7 are farthest from the oil pump, it is a very good chance that there is sludge built up around the valve springs not letting them close.

 

Yeah very well could be. These engines don't just bend lifters or rods from a guy gunning it. Must have been some neglect going on as far as maintenance goes. It will be interesting to do the "surgery". Let us know what you find and take some pics.