Disco2 Rocker Arm Oil Clog

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robert.juric

Active member
May 16, 2017
39
0
North Alabama
So after replacing everything else chasing a persistant misfire on #8, I spoke with an independent Rover shop who thought I may be looking at a worn cam. So during the tear down I decided to pause at the rocker assemblies and check them out. They were the only thing I didn't replace or have someone clean for me. Upon closer inspection I can see that the rocker arm is clogged where it meets the pushrod. Is this something that could cause my misfire? I suppose I'm wondering if this were serious enough to cause a misfire then I could clean up the rocker assemblies properly button it back up and test it again, or should I continue to tear it apart and inspect the cam?

I've attached some pics.
 
squirt

squirt

Well-known member
Nov 13, 2008
824
13
Los Angeles
That's not great, but it's not going to cause your misfire unless it has caused some secondary, physical damage. The center channel of the pushrod acts as an exit port for the oil from the hydraulic lifter. If the channel is blocked, the oil will just leak out at the base of the pushrod. It restricts some lubrication for the rocker arm, but that won't cause a misfire on its own. If your rocker shaft is broken, that's another story.

Assuming you've been through all the easy/typical misfire diagnostics, the most likely cause is either a collapsed/worn lifter, or a bad cam lobe. My recommendation would be to clean the rocker assemblies and pushrods to eliminate the issue you've identified, then pull the lower intake to access the lifters and cam for inspection.
 
squirt

squirt

Well-known member
Nov 13, 2008
824
13
Los Angeles
Yep, just grab your dial indicator and measure the lift numbers through the rough openings in the bottom of the valley.
RR-Engine-095.JPG
 
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robert.juric

Active member
May 16, 2017
39
0
North Alabama
May be a simple question, but is there any issue turning the engine by hand? I started to do it yesterday to check that the rocker arms were moving properly. I heard a hissing noise which made me a little nervous.
 
squirt

squirt

Well-known member
Nov 13, 2008
824
13
Los Angeles
It's not a big deal, but turning the engine is probably a PITA. The hissing is pressure releasing, since you removed the rocker shaft and closed all the valves. There's no risk of valve/piston damage, since the valves are all up, but to make life easier, I'd remove the spark plugs to prevent pressure buildup.
 
rovercanus

rovercanus

Well-known member
Apr 24, 2004
9,651
246
squirt said:
That's not great, but it's not going to cause your misfire unless it has caused some secondary, physical damage. The center channel of the pushrod acts as an exit port for the oil from the hydraulic lifter. If the channel is blocked, the oil will just leak out at the base of the pushrod.
Click to expand...

D2 engines have solid pushrods.
 
rovercanus

rovercanus

Well-known member
Apr 24, 2004
9,651
246
The top of the push rod won't have as much oil on it. Other than that, it's doubtful this is any cause for a mis-fire.
 
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robert.juric

Active member
May 16, 2017
39
0
North Alabama
So I pulled the lower manifold this morning. I'll post the lift numbers once I measure them.

I noticed a few things. There was coolant in the last 2 intake ports on the heads (closest to the firewall). I think this was spilled while removing the lower manifold (probably, right?) If coolant were leaking it likely wouldn't be on top of the valves would it?

Also, some of the tappets don't want to pull out easily. The freely move but don't want to pull all the way out freely. I just wanted to make note in case that is worth replacing?
 
squirt

squirt

Well-known member
Nov 13, 2008
824
13
Los Angeles
robert.juric said:
So I pulled the lower manifold this morning. I'll post the lift numbers once I measure them.

I noticed a few things. There was coolant in the last 2 intake ports on the heads (closest to the firewall). I think this was spilled while removing the lower manifold (probably, right?) If coolant were leaking it likely wouldn't be on top of the valves would it?

Also, some of the tappets don't want to pull out easily. The freely move but don't want to pull all the way out freely. I just wanted to make note in case that is worth replacing?
Click to expand...

The coolant is almost guaranteed to be spilled from removing the manifold.

That is pretty typical for worn lifters. They get "mushroomed" over time from wearing on the cam. It doesn't mean they're not doing their job, but it does mean that you'll need to pull the cam to get them out, should you need to replace.
 
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robert.juric

Active member
May 16, 2017
39
0
North Alabama
I wanted to follow up to close out my own post.

I tore everything down to the rocker assemblies. I soaked the rocker assemblies and rocker covers in a strong degreaser (PurplePower) to clean them up. They were filthy. I also replaced the oil separator while I was at it. Nothing else was replaced besides the necessary gaskets/orings. After putting it all back together my misfires are gone. It could have been a very dirty/stuck rocker assembly component or an electrical connection that was reset more securely upon reassembly. Who knows. I'm just glad to have my Rover back!

Here is a pic of my initial reassembly with half-assed cleaning of the rocker assemblies:
https://www.flickr.com/photos/robertjuric/32904451341/in/album-72157675889696415/

Here is a pic after tearing back into it and giving the rocker assemblies a proper cleaning:
https://www.flickr.com/photos/robertjuric/35750773414/in/album-72157675889696415/
 
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