I have a '98 Discovery Series I with about 87k miles on it. It has been running beautifully and has been maintainence free (for a Land Rover). But in the last few months I have noticed an odd sound on start up. I comes for just a few seconds just after the first start of the day, or after the vehicle has been sitting a few hours. At first i thought it was a weak lifter. The sound goes within a 2 seconds after start up and it setteles into a normal idle until I put it into gear and then I hear knocking as I move away (almost like a rod knock) but it quiets up above 2k rpms and is completely gone when the engine is warm. It has been doing this for about 3-4k miles now and I don't notice a loss of power and it is not using any oil. I have used the engine cleaner for the last couple oil changes and on the last one even ran transmission fluid through the engine at idle to clean any carbon out. The oil stays fairly clean (using 10W-40) and nothing seems wrong. I just don't like that noise! Is she on her last legs? I am the second owner. Many thanks in advance.

 

Stop driving it if you don't want your engine to fail.
What oil filter , by brand , are you using?
I would suggest you do an engine flush, using 6 qts of ATF and then pull the oil pan for a good cleaning and inspection. Make sure to check the oil pick up tube to make sure it is tight and not plugged. Look at the inside of the pan to see if there is any unusual metal parts, or unusual piles of metal filings.
Get back to me.
Mike

 

I have run ATF through it twice but have not removed the oil pan to inspect. The ATF was quite dirty the first time but it was clean the second time. Should I run the ATF through it again before I remove the oil pan? Anything else you recommend me to do? Thanks for the reply.

 

Also Mike, is there a way to also find out if a lifter is weak and if so which one? Where does the oil pressure sensor sense from?

 

I would pull the oil pan and clean and inspect, you don't need to do a flush again.
What is important is the inspection, looking for unusual wear, too much extra metal in the pan or a pluged up oil pick up tube.
Don't worry about the oil pressure and where it is sensed from, it is under the front cover and you don't really want to go there. If any thing have a mechanic hook into the engine block, usually around the oil filter area, and see what sort of pressure you have when cold at idle and at 2000 RPM's and the same when the engine is at opperating temp.
Mike

 

I would use a stethoscope to find out if the noise is coming from the top or the bottom end of the engine. Have a mechanic do that if you don't have one, but you can buy a stethoscope for a few dollars...If top, then you have a valve adjustment issue (unlikely given your description). Your problem is most likely the bottom end which could be piston slap - too much piston to bore clearance - or a rod knock. You could send your used engine oil for analysis - if it is piston slap, then there would be traces of aluminum in the oil. If it is rod knock then you will likely have traces of copper - meaning that your main bearings are worn all the way through to copper. The oil analysis should come back with an explanation of the results. Napa stores that have service centers will usually do this. Make sure the oil has been in the engine for a couple thousand miles before you take it in.

As for driving the truck, you mention that the noise goes away within a couple seconds of startup provided you don't put the engine immediately under load (as in shifting into a gear). So why not just let it idle for a minute before putting it in gear. Then when you shift it into gear, you won't hear the noise... let us know if that is in fact the case.

Piotr

 

There are a couple things to mention regarding the engine noise. First-- when Land Rover moved to a distributor-less ignition, they no longer controlled the end-float of the camshaft with a helical gear (that used to drive the Distributor). They had a problem with "Camshaft walk" that would produce a noise as you describe. They then had a TSB to check the end-float,and there was a nylon "bumper" installed to control the walking. In subsequent years they had a thrust plate design to locate the Camshaft, but it was found that when engines accumulated miles, either because of a bad heat treat of the friction surfaces, or just inadequate manufacturing tolerances --- the gap would widen, and the noise would occur. The fix then was to replace the camshaft. So-- you may be experiencing the beginning of a Cam-bump noise because of too much end float. Not really a major problem, but it will wear the timing chain and gears prematurely, and cause a little slip in cam timing.

Secondly-- the rocker arms and shafts that they pivot on--- are a known weak area on these engines. As are the tappets (cam followers). Because this is a hydraulic valve train with no adjustment, the only fix for what some would describe as sounding like "too much valve lash" is to re-new the rocker shafts and arms--- and in some cases fit a new set of lifters. Now-- to complicate things further, there is some evidence to support the theory that the reason for the premature wear on the valvetrain componentsmay be compoundedby oil pressure delivered from the pump in the front timing cover is not beingwithin spec. The "bottom end" on these motors is pretty tough, but oil pressure finds its way to the valve train later on in the circuit, and so any sustained pressure below spec can aggravate things. We have gone through a total changeout of valve-train components in an attempt to cure a engine tick, only to find out that the oil pump housing was scored, and had to replace the assembly.

This is why those of us that frequently contribute to this forum recommend that a oil pressure gage be fitted to the front timing case cover where the oil pressure sending unit screws in-- and the actual values recorded (cold engine at idle, warm engine at idle, 2500 rpm value, etc.) --- if unusual engine noises are present.

The bottom line here is that oil change intervalsare VERY important on the Land Rover engine. And-- so is the quality of the oil used.

And --- the recommendation to take a oil sample and have it sent in for analysis-- is a good one. Private pilots do this on their Lycomings and Continental engines as a matter of regular practice so they can assess the overall condition of their engine, and avert potential disasters. It used to be considered a little overkill for street-drivenautomotive engines. But have you priced the cost of a replacement engine for a Land Rover recently? Think in the range of $8500-10,000 and all of a sudden a $29.00 oil analysis doesn't sound out of line.

Regards,

Geoman
www.eurotekapg.com

 

I agree with the analysis. I do one at every change. If you keep in the routine, you can pin point what is filing by the metals you see in the oil. It is only $30 more for most people, and it is a helpful insight. Doing one when you first get a problem might not help you as much as doing them more regularly, but I understand cost might prohibit this. Running a good synthetic oil is the best way to keep out the gremlins, but it won't cure it if they are already there.

Good Luck with your finds.

 

Thanks for all the replies guys.

Poitrsuw. I hear the noise on startup for a couple seconds, then I hear it when I put it into gear, especially just above idle (about 1000 rpms) even if I wait a couple minutes before I put it into gear.

I will try to have a mechanic look at it tomorrow and also do an oil analysis. It is not my primary vehicle so I can leave it sitting until I have time to get into the oil pan next week. If it is the bearings, how easy is it to replace them at the bottom end? Maybe I am getting ahead of myself here. I will look into all your suggesstions.

Thanks again for all the help guys. I sold a perfect engine from my old wrecked Discovery a few months ago, now regreting the decision.

 

That is a little different than the noise I have experienced.Theknockhappened on an engine if it was started and immiediatly put under load. If I waited for afew seconds and then shifted into gear the noise wasn't there.

Let us know what the mechanic & oil analysis uncover.

Piotr