intermittent oil warning light coming on, tappets clattering
 

hi guys. (and gals) I have just moved up into the p38 world, and bought a very nice 4.0 se 1997 .110,000 miles. (LPG) everything seemed ok on the test drive. no faults, or issues. apart from a/c book light showing etc. however, whilst driving home, after about 10 miles, the engine suddenly started to clatter a lot, so dropped the revs immediately, and the oil warning light was on. -i thought, 'well i checked the oil, it was a little high, (3/4 inch over, but clean(ish'). (car has full main dealer service history)I immediately stopped. tried to start after a quick look under the bonnet, car was very tappetty, like it had run out of oil. bottom end sounded all ok. (coolant temp was fine) i waited about 10 mins, started and all was fine again. i drove very slowly back home, and as soon as it came on again, pulled over. after a brief rest, the car fired up silent. (after a gentle rev to prime the tappets.)
I'm thinking the oil is starving from the top end. should i consider the oil pressure relief valve? looks easy/cheap to replace. however, i bet it would be perhaps a loose pick up in the sump. or a dodgy oil pump.There areno leaks, no sump dents, never off road, no back pressure, and just had a main dealer service. has anyone had anything like this. the missus is very dissapointed, as she wanted to show her friends, but its now sat here, untill i have some time to change out a few things, before i take out again.
Don't you just love buying cars eh?

p.s. had issues in the past with priming an older v8 engine pump, with vasalene, i could get a few basic parts together like the pump gears gasket, sump gasket, relief valve, filter, and new oil etc. could the cooler be blocked.? looks to be well maintained, and no steam cleaning done. hoping to remove sump also to change the pick-up 'o'ring and flush the pick up out.

RE: intermittent oil warning light coming on, tappets clattering
 

First thing you do is quit driving it cause you can't afford to replace the motor that is about to gernade.
Find a mechanic that can be trusted, have him to a oil pressure test at all 4 points, cold at idle, cold at 2000 RPM, operating temp at idle and operating temp at 2000 RPMs.
Donot drive it till you get it into a shop, I promise you, you will loose the engine if you do.

RE: intermittent oil warning light coming on, tappets clattering
 

dont worry its not going anywhere, till i have a chance to examine a few things.was only a very short drive from home, but i wasbarely throttling it. i guess if the heads are clogged, or the strainer is clogged, then starvation will let the top run dry, and the bearings run below normal pressure. also, if the pick up pipe 'o' ring has failed, then air drawn in will cause similar. I have no doubt that there is low oil pressure. maybe just the releif valve sticking. I will be having a look next weekend, as I have plenty of time then. -perhaps a loose filter seal could be the culprit. (but it feels tight at present. ) at worst the pump gear could have broken, and may be holding in intermittantly? i will remnove a conrod bearing or two, and check those once i get the sump off. Just wondered if anyone has had a similar experience. I'm pretty handy with a spanner, -you have to be to run a land rover. i will post any helpful advice/remedy soon.

RE: intermittent oil warning light coming on, tappets clattering
 

Your oil pickup strainer is picking up sludge from the bottom of the oil pan and starving the oil pump. When RPM falls, the suction from the pump falls too, and the cack drops out of the screen back into the pan. Rev it up, and it sucks it all back up again.

GEMS motors are famous for caking up inside. The culprit is the poor crankcase ventilation system. It will be neccessary to remove the pan and clean it,and the pickup screen.

Once this is done, remove both engine breather hoses from the valve covers. Look inside the fittings on the valve covers, and you will find little plastic baffles. Remove them. It may be neccessary to remove the valve covers and punch them out from the inside.

Next, find the vacuum fitting on the right side of the intake plenum. Using a 1/8 inch drill, drill through the fitting to clean the orifice. Do not enlarge the orifice, as it is part of the idle air circuit.

Replace the breather hoses if necessary. Now your crankase ventilation system will work as it was intended. Idle quality should be dramatically imroved also.

change your oil often.

Next!

RE: intermittent oil warning light coming on, tappets clattering
 

great post, thanks, i was almost 'hoping' it was something as straightforward as this. I will report back soon with the results, after the coming weekend and maybe a picture or two.Iseem to be losing some oil down the rear of the engine, (its oil wet) possibly due to crankcase pressure pushing out the intake rear rubber gasket. (happended on an old v8 I had) so i will take off the rocker covers too. will also check the big ends to see if the previous owner hadn't nipped them up. thanks for the tips, speak soon. (-after my 'dirty weekend')

RE: intermittent oil warning light coming on, tappets clattering
 

you were right! the sump came off easy as pie with the suspension up, the strainer had the dreaded 'BLACK DEATH' and so did the rocker covers too. the sump had thegastly 'black crumby matter' in the bottom. Igave all the deseased parts a good scrape and flush, and removed the baffles in the rocker covers, jeez the coverswere attrocious! removed the inner plates too to clean behind, and then replaced those.I cleared the tubes and ran a drill through, cleaned the plenum, removed the rockers shaftsand used a long woodscrew to tap through and draw out the black death in the feed oilways from the block, and rinsed out the rocker shafts. all back together - i put in a new set of conrod bearings, as they were showing copper on the tops, (116k miles) I used an oil treatment with some fresh oil, and ran and removed it. fresh oil again, plus another filter, and i guess it was like giving a heavy smoker a lung transplant! ticks over sweet as, thanks guys. its running great! this is actually a full dealer stamped at 12k intervals, car, that was close to having a coronary embolism!

RE: intermittent oil warning light coming on, tappets clattering
 

Need to do an ATF flush to really start removing all that build up.