Hi all,

I've had this noise for a while, this past year or so and started out as a subtle noise but of recent, it's gotten to be very noticeable. I am not 100% sure but I recall that I would only hear the noise after engines gets hot but it's now noticeable on cold starts as well.

Car runs fine, nothing out of the ordinary. Never had overheat on this vehicle and no check engine light. I have bluetooth obd11 reader and no issue reported.

I've searched and thinking that this maybe a valve train issue and concerned that this maybe something serious or shod be immediately looked at.

I've removed the belt to eliminate accessory components and noise is still there. My best guess of location would just below the plenum/throttle body. It does increase with rpm and guessing roughly half the idle speed so probably related to valve. I will probably take this in to shop but wanted to get some input first. Thank you in advance.

'98 Disco LSE w/ 155k, stock.


Video of noise:

 

The video sounds like my 98 LE's ticking but louder. I'll be interested in what you find.

 

Almost 99% of the time valve train noise is due to lack of oiling. If you've never taken the rocker assembly apart (easy, it's a shaft) then I'd say it's due. These engine produce more than a fair amount of sludge. That sludge becomes very hard (crystalline) due to the high heat with original temp thermostat. The shaft and rockers are usually the fault. I can clean them in less than one day, non-skilled might take a weekend plus. The other item is a lifter that is either collapsed or not getting oil through it's oil port. Super easy stuff but it does require at least the valve covers to be removed..... The lifters require the intake to be removed and the valley gasket to come off.

 

2X on cleaning and checking the rocker shafts and rocker arms......fwiw, I had a similar issue that got made worse noise as the engine warmed up....turned out to be a couple of loose inserts in the rocker arms where the push rods land.....the steel insert would loosen up in the aluminum rocker arm and create the dreaded tapping noise....
you can remove the valve covers and run the engine to narrow it down a little further.....it wont spray much oil around at idle and itll be easier to pinpoint the problem

 

Thanks guys. I'll go ahead and go the suggested route and take a look under the valve cover. I suspected I would have to do that based on doing some search on this forum but wanted to be a little more certain. This isn't my daily driver so not in a hurry but for me, it'll probably be at least a full weekend job so will need to set aside some time.

I probably won't be able to get to it for at least a couple weeks so I'll report back once I get in there. I also suspect that I'll need some further assistance once I open this up with pictures but have saved a few links to old posts on valve train issues.

Based on old posts, I believe I will need the below items:
1. Gasket maker/RTV for the plenum to engine.
2. Valve covers need gasket
3. 8mm/5/16th 12pt socket and other tools that I have
4. Parts - since I don't know root cause, i was planning on just taking a look then ordering the parts but not sure if you all recommending replacing parts as preventive based on mileage/age of vehicles

 

that does not sound bad but I hear a massive vacuum leak


I agree with scouts pull the valve covers and clean the rocker system, I had to sort of beat mine apart it was so stuck together from burnt crusty oil buildup, I took mine apart and cleaned everything with a fine brass wire wheel on a bench grinder comes off easy without scarring then just lube the hell out of the parts with fresh oil for reassembly, lay out parts to not mix em up, check my thread for pics


a missing rocker tip is loud like bad lifter not your noise

 

Intake gasket incase you lift the intake manifold off to get to lifters. There is a little known but great product for loosening or completely dissolving oil and varnish and comes in a gallon can with a stainer, name brand would be Gunk but there are others. It's a mini dunk tank, works great for soaking parts overnight and then using compressed air to force out passageways. I highly suggest it. I used this on cycle carburetors that had sat for years with old fuel in them. It was my secret in a can and I had a ton of old bike restoring business by word of mouth because I could rebuild and sync original multi-carb setups to better than factory. Works like a charm on rockers and there is no finish on them to worry about peeling off, just occluded oil passages.

Until you actually get into the valve-train I would wait to order parts. Do you own a micrometer or set of vernier calipers? Those are well worth their weight to own.

 

Tom - you have very good ears, yes, I think there is a leak somewhere around there but not sure I plan to dig around and see if I can find it. I've tried spraying carb cleaner around and could not detect anything yet so it may require a more detail inspection. Also, recording this on my phone, the tapping sound is coming out a little louder...it might have something to do with the noise cancelling on the phone. I was at first worried the sound would be drowned out by the engine noise and hissing.

ihscouts - I will look into the Gunk and I do have both micrometer and vernier caliper (hand me down from my Dad's metal working days in)

 

There's only a few places to leak vacume

Check each hose good coming from the valve covers, fuel pressure reg. And vacuum booster, unless the MAF boot is bad or you are missing the boring on front of MAF

Think beyond that your talking plenum or intake leak, or gasket on iacv

 

Decided to tackle this project this weekend as I had to cancel my fall trip up the the mountains.

So far, I've remove the cover on driver side, decided to take the plenum apart as it looks really crowded, see attached picture. Everything seem to be in place solid with no movement or anything looking worn. I have a few questions to ask before I move on to taking it apart.

1. Reviewing Rave, seems straight forward but to confirm, I remove the 4 bolts on top, mark the rods to ensure proper sequence.
2. Before I do anything else, should I place the plenum back and run the engine to see if I can locate the noise? Everything seems okay on observation so tempted to just take out the rocker and giving it a good clean.
3. The driver side cover seems lodged underneath the rules lines on the inside an coolant hoses on top, I managed to get enough room to unscrew but have temp put them back. See attached picture but wanted to get input if that's the only way to get enough room to remove the covers.
4. The rubber gasket for the cover, is that reusable or should I get a new one.