Should have knocked on wood..

[Tom in MD]

96 4.0. Original owner. Been very lucky so far, but now, at 130K, I'm starting to hear some valve knocking under load. If I easy off the gas, or drive with less of a lead foot, I don't hear anything out of the ordinary. I wonder how much time I have before blowing something up. Any thoughts or anecdotal information would be greatly appreciated. I'm interested to hear from you all.

1) How long after first noticing this symptom you either had work done or had a major malfunction?

2) Did you spend big bucks(>$2K) on repairs ?

3) What did you have done or do yourself ?

4) Money well spent ?

Thanks guys !

 

[Jasrover]

I have been hearing the same thing for a few weeks. Only under load with my foot into the gas. At first I thought it might be a cat rattling, but it could also be the valves. Anyone have any ideas?

 

[Tom in MD]

Just us ?

I guess it's just you and me Joe. I'm pretty sure it's a valve tapping. Mine sounds more like one valve rather than valve symphony you hear when you start up on a cold day. Only under load, but taking less and less load to recreate the noise. That scares me a bit. I can sit still, foot on the brake, give it some gas, and make it happen. I've always been good about oil maintenance. I wonder if any additives might clear this up or prolong life. That's my next level of investigation. I'll keep you posted.

 

[jmonsrvr]

are you sure its a valve or in the engine? its funny that the sound would only be heard under heavy loads and acceleration. are you sure its not a loose plug or wire? this can often cause a ticking sound that sounds likes its in the engine...

 

[Ho]

try a quart of marvel mystery oil with fresh oil change.

 

[mikem]

99 D2 doing the same thing

My D2 with 38k miles started doing the same thing this weekend.

Someone suggested either values or the exhaust manifold.

I'll post more when I have more info.

Mike

 

[Tom in MD]

I thought you were pulling my leg..

Marvel Mystery Oil ? I thought you were joking, Ho, until I looked it up. I'll try it and post back. Thanks for the tip !

I inspected the exhaust manifolds and found no defects or cracks. Not sure if the Cats are bad, but it sure sounds like a rogue valve.

 

[dent]

have the same problem though my knocking is constant and when i rev the engine up knocking picks up too... been happening for about 6-10 months but since i only drive the thing once or twice a week, keep forgetting to look into it more. Taking my plugs out this weekend and seeing if it might be detenation. will keep you updated as well

 

[geoff]

I'd run a can of SeaFoam through the intake. Helped my sort of a muffled knock sound under acceleration. Might take a couple applications. Eventually you won't see any white smoke anymore. Valves "tap".

 

[anthony]

could very well be those damn 6 bolts where the manifold meets the y bar! sounds just like a valve (especially after a few beers!) I had never touched my exhaust system nor had anyone else (at least not in last 20k), then one fine fall day hitting pavement after an outing it began to sound a lot like a valve issue! tightened up those 6 bolts and sounded like a mosquito fart again!
all i am saying is that those things backed off in a matter of hrs, i was very happy when it turned out to be nothing,
may want to check this out!

 

[anthony]

best way i have found to check manifolds for tiny tiny cracks is seafoam! when you start er back up, just stick your head under the hood a look for the smoke cloud!

 

[Tony23007]

Engine Knocking

Are you guys hearing engine knocking or engine pinging. These two are hard to decipher and from what I am hearing it sound more like engine pinging since its happening under load. I had the same issue on my Disco-95 and it ended up being the timing. On a 96 or above since there is no Distributor I don't know the answer but if you guys are running lower than 91 Octane, I would suggest running 91 Octane gas, and see if you notice a difference. Engine pinging is caused by poor combustion, higher octane will help that with that problem.

 

[Tom in MD]

It's a knock

Sure sounds like a knock rather than a ping. Next fill up I'll hit the 93 octane just for grins. I'm not noticing any power loss, not that it ever had power to begin with, just the noise. I've done my oil change, complete with a quart of MMO, and some in the fuel tank too. No noticable difference yet. I'll keep playing with it. If it was a valve, wouldn't I notice a stumble or some other engine performance issue ? Maybe throw a code or two ?

Not ready for Seafoam yet. I need to let some of these other scenarios play out. I'll definitely give it a shot later, though. Thanks..

 

[Gabe]

Are you hearing a knock or a click?

Valve lifter clicking ( AKA clatter ) will often be improved by running mystery oil or Rislone. Both will clean the lifters and oil galleys.

A valve tick will sometimes be caused by worn rocker shafts and rocker arms. A better oil viscosity can help lesson the clatter ( 5W50 or 20W50 if in the south ) but, the real fix is new rocker shafts and rocker arms.

Sticking valves sound like a wrist pin only it?s a single rap. it?s independent of load and usually gets better after motor warms up. Will usually through a check engine code. when valves sticks open and suddenly slams closed, it makes the ping sound and also caused a loss of compression while it was open. Once it gets bad enough, the check engine light will come on.

What you are describing sounds more like Pre ignition or more likely a main bearing starving for oil.
This would sound similar to a diesel sound when you put a load on your motor.

If your noise sounds most like the last description, I would do the following:

Get an oil pressure test done, worn mains will cause low pressure at idle ( rovers normally idle between 15-25 PSI with good bearings) and should have no problem pumping up to 40 PSI at 2000 RPM.

If oil pressure is low, check pressure relief valve is not stuck open. Many a motor has wiped out mains and rods because pressure relief valves didn?t work correctly.

Next drop the pan and see that oil pick up screen is not clogged with gunk.

Even if oil pressure looks good, you could have a clogged oil way in the crank that is starving a set of rod bearings and a main but that would sound like a power stroke diesel even at idle.

Don?t drive with a knock,

Do a oil pressure test or drop the pan. Both of these things can be done in one day in about 2 hours if you take your time. Avoid the temptation to pull a rod cap off or a main cap off. Once you disturb a used bearing, you shouldn?t put it back in. To replace the bearings involves pulling to motor and turning or at least polishing the crank but at least you will know what it is or isn?t

Sorry for the long post but if it?s really a knock and not ticking or clatter, you will further damage an other wise reusable crank trying all the sea foam, tighten exhaust bolt snake oil stuff.

GG

 

[CaptainSpalding]

Marvel Mysery oil

Marvel Mystery Oil ? I thought you were joking, Ho, until I looked it up. I'll try it and post back. Thanks for the tip !

I've used Marvel Mystery Oil to bring several totally dead engines back to life. Great stuff!

 

[Tom in MD]

Update

So far, I've used MMO, switched to 93 octane, and inspected exhaust manifold and the infamous "6 bolts". What seemed like knocking has evolved into more of a hollow-metallic tick. Like hitting a can with a screwdriver. Still only under load, and more frequent after getting up to operating temp. The noise seems to be comming from beneath the passenger-side, towards the catalytic converter, if not eminating from the converter itself. Final questions for the group, then I'm seeking professional help (for the Disco):

1) Runs strong and no codes. If it was valve-related, shouldn't I have more symptoms?

2) If the catilytic converter, what's the worst that could happen? What's actually going on in there, blockage ? Rusted out ? Exterior looks OK.

3) MikeM, Jasrover, still having this issue? Any changes ?

 

[Jasrover]

update

Tom,here is an update. I tried Seafoam first and did not notice a difference. I have always used 93 octane since the disco was new. My noise sounds exactly like yours but it has slowly evolved. At first it was only under hard acceleration, but now it happens under light acceleration also. It does not happen when the engine is cold,only when at normal operating temp. I also hear a faint knocking sound at idle which was not there before. I tried the MMO this weekend and will let you know if it helps. If it gets much worse I will probably take it in,as one of the previous replies has me worried about a starved bearing. Joe

 

[RVRSRVC]

Tom,
A catalyst element that is breaking up will pass a lot of the small pieces out of the tai;lpipe, but some of the larger pieces can get stuck in the muffler. Theoretically, the element could break up and get lodged in the outlet of the convertor-thus ending the rattle, but than the cat ends up 'tinny' sounding all of the time.
One of the the first things we look for when we see a vehicle with this complaint IS a loose cat. Ususally on the right side! It's not very scientific, but you can kick the y-pipe with the engine off and listen for a rattling sound. I said it wasn't scientific, but it is effective! As long as there aren't any loose exhaust clamps or hardware, I would be willing to bet the cat is loose.
I don't remember hearing anything like a loose cat when we saw your Disco, but feel free to call me. I 'd be happy to try to assist over the phone.
Trevor

 

[Tom in MD]

Thanks..

Thanks Jasrover. Some of what you said is true for me too: "but now it happens under light acceleration also. It does not happen when the engine is cold,only when at normal operating temp". After driving home from work yesterday, I had the rover sitting in the garage, running in neutral with the e-brake on, and it was just barely making the sound. And like yours, when I first start out cold, no sounds at all. Keep me posted, and I'll let you know how things go on my end.

Thanks Tevor. I'll give it a few good kicks and see if anything shakes loose. This issue didn't come up until a few weeks after I was over at your place. I'll definitely be giving you a call.

-Tom

 

[plus_ar]

similar noise / concern

Does anyone know how these two issues ended? I've got a similar situation. There is no noise while the vehicle is cold, but once it gets up to normal operating temp, there it is. not super loud, but annoying to me and I would like to take care of it soon. definitely eager to hear if you guys had some sort of fix.

thanks,
greg