| Author | Message | ||
     Craig McLaughlin (Cmclaugh) Member Username: Cmclaugh Post Number: 46 Registered: 06-2002 |
Under load while accelerating my 99 D2 clatters. The noise sounds kind of like a muted diesel engine. Power is good and the engine idles smoothly and quietly. The clatter happens more when the engine is hot and under load. Could this be sign of bad valves or lifters? I've also read a few post talking about bad rocker arms/shafts could this be my problem? Vehicle only has 60k on it. Is this typical of the Rover V8 and should I just get used to it? | ||
| Geoff 93 RRC (Geoff) Member Username: Geoff Post Number: 105 Registered: 11-2002 |
I had similar symptoms - mild diesel sound at low speeds when accelerating only. Chased a lot of different things. In the end I think it was actually u-joints. I replaced mine since I have a lot more miles. When were yours greased last? Apparently common the the later 4.0 engines - the idler pulley gives problems. There is a TSB somewhere. The bearings wear and rattle a bit. Do a search. I replaced my v-belt (similar) tensioner pulleys for same. I also replaced most of the bottom end bearings (not an easy job) which has raised oil pressure. I also retarded timing. It all probably helped, but the last 2 aren't likely applicable to you since at 60K the bearings should be fine and I don't think timing is adjustable on the D2. The rocker arm defect(another TSB somewhere) could open up clearances similar to mushy lifters caused by low oil pressure. The last thing I did was to let the motor inhale some water through a small vacuum hose to the intake plenum. The idea was to get rid of carbon deposits that can collect on the pistons and bang the heads. Supposedly this gets worse when the motor is hot. Anyway I think the carbon was removed since I later dropped the exhaust Y-pipe and the top of the pipes/headers were absolutely clean of carbon. | ||
| Geoff 93 RRC (Geoff) Member Username: Geoff Post Number: 107 Registered: 11-2002 |
Oh, and check for exhaust leaks at the Y-pipe to header and y-pipe to tail pipe. Cracked headers can also make tapping like sounds. | ||
| Craig McLaughlin (Cmclaugh) Member Username: Cmclaugh Post Number: 47 Registered: 06-2002 |
So say it's the rocker arms/shafts that need to be replaced. On a D2 how much trouble is it to remove the valve covers and swith them out? Would I need to remove the entire intake manifold assembly? Are there any gaskets I should purchase ahead of time? | ||
| Bruce Potier (Brucep) Member Username: Brucep Post Number: 65 Registered: 06-2003 |
I would isolate the noise first. If you feel strongly it's from the rockers, pop the valve cover. You could isolate the specific rocker arm and replace the offender or switch-out the entire assembly. While you are there, check the p-rods for issues. PS, you can check for offending rocker by either running engine (messy) or going through the TDC cycle for each piston on that bank and determine the offending rocker. If I were you, I would first ask someone else to listen and see if they beleive the rockers are your source of noise. Good luck. | ||
| Edward Bibb (Heirless) New Member Username: Heirless Post Number: 25 Registered: 04-2003 |
lets eliminate the obvious. Are you using Premium unleaded fuel? This symtom is normally referred as preignition (fuel igniting before the piston is TDC). Saving a few dollars at the pump isn't worth the potential harm your engine may be exposed to. | ||
| Craig McLaughlin (Cmclaugh) Member Username: Cmclaugh Post Number: 48 Registered: 06-2002 |
I agree, I don't want to jump the gun and get into expensive and time consuming repairs that aren't necessary. So far, I've checked the exhaust manifolds for cracks none are visible to the naked eye. Earlier this year, I re-tightend the bolts connecting the exhaust manifolds to the Y-pipe as they were very loose. I was getting a loud raspy noise under acceleration. Tightening the bolts solved the problem. I wonder if the gaskets are still leaking a bit resulting in the noise I am hearing now? I bought the vehicle used so it's hard to say how long it was running that way. Vehicle is in tune with new air filter, Bosch Plat. plugs, ignition wires etc... I also run premium unleaded gas. About the highest octane you can get at my altitude (4500') is 91 so hopefully that will do. Engine idles good and runs smoothly at speed. There is no excessive valve/lifer noise at start-up as compared to a 96 D1 used to own. Still trying to get used to that one. I run 15w 50 Mobil 1 in the summer and 5w 30 Mobil 1 during the winter months. it could be my imagination but I swear the clattering is slightly more subdued with the heavier oil which leads me to think the problem is valve train related. What else should I be looking at? | ||
| Rob Davison (Nosivad_bor) Dweb Lounge Member Username: Nosivad_bor Post Number: 1035 Registered: 02-2003 |
very slight chance a motor mount is broke and the fan is rocking up into the fan shroud on exceleration and thats a sound you are hearing, though it'd say it's about a 5% chance because of the sound you named and becasue usually you have to be on it pretty good to hear it and going up hill. rd | ||
| David Huddleson (Dhuddleson) New Member Username: Dhuddleson Post Number: 3 Registered: 09-2003 |
I have what sounds like a similar situation with my vehicle. I have a 98 Disco V8 with about 70K miles. Have checked for exhaust leaks etc., no problems there. At any time with warmed-up engine, light knocking is audible at idle. First noticed at least one month ago, and does not seem to have changed since. When engine is cold, no knocking seems apparent. Once maybe 3-5 minutes of warming up have passed, light knocking is heard at idle speed, towards rear of left side rocker cover (used a stethoscope to attempt to pinpoint). Changed rocker shaft on recommendation of dealer, but no difference. Fuel economy seems normal, performance seems normal, idle seems fairly smooth... Opinions from Robison (Hi, I'm sure you're lurking...) suggest to investigate lifters, wristpin or possibly a dropped cylinder sleeve (gulp!). Second two options involve a lot of effort and cost... As I have 72K Service coming soon, I was going to have some investigation done at same time! I am interested to hear any further developments or other's experiences... DH | ||
| Edward Bibb (Heirless) New Member Username: Heirless Post Number: 26 Registered: 04-2003 |
Rob has a valid point on the fan contacting the shroud. Seems the easiest diagnosis is to check the fan tips and the shroud for damage. Lets hope motor mounts are the issue and its not a deeper issue. | ||
| Craig McLaughlin (Cmclaugh) Member Username: Cmclaugh Post Number: 49 Registered: 06-2002 |
The clattering/knock noise I am experiencing is only when the engine is under load such as accelerating briskly or climbing a step hill at a low speed. Cold start-ups are normal with no excessive noise. With the engine idling there is also no noise. You can even rev the engine while in neutral with no load on it and their is still no noise. As best as I can tell it's coming from the passenger side of the engine bay. I have checked for manifold and exhaust gasket leaks and haven't found any. My big question is why only under load? If a lifter is going bad or there is excessive slop between the pushrods and valves wouldn't you hear a clatter at all engine speeds and loads? | ||
| Geoff 93 RRC (Geoff) Member Username: Geoff Post Number: 115 Registered: 11-2002 |
If the noise varies in tempo more with speed than with rpms then suspect the drivetrain. | ||
| Craig McLaughlin (Cmclaugh) Member Username: Cmclaugh Post Number: 50 Registered: 06-2002 |
It's not a rotational drivetrain noise it is definetly coming from the engine. You'll be going down the road with no noise. Push the accelerator and as the engine accelerates you get the clatter. Let off the gas instantly and the noise goes away. It's a clattering muted diesel kind of noise. Using a stethoscope and with the engine idling valve train sounds normal. No loud ticks, clacks or anything from any of the cylinders. Even when I rev the engine in neutral there is still no noise. If it is indeed a valvetrain tolerance problem or leaking lifter why wouldn't it show itself during cold start-ups? | ||
| Geoff 93 RRC (Geoff) Member Username: Geoff Post Number: 117 Registered: 11-2002 |
Here is the TSB on the rocker arm problem: http://www.nhtsa.dot.gov/TSBScans/sb618833.pdf. Check your VIN. Other things to check are the flex plate bolts are tight and not hitting bell housing or that the flex plate is not cracked. The flex plate can be seen by taking off the half moon plate on the transmission housing next to the oil pan. As an aside, these engines operate at very low oil pressure relative to other makes - 30-40 psi at 2400 rpm, 10-15 psi at idle (hot). As a result lower viscosity oils seem to bring out all of the noises, especially when hot. Thicker 20w-50 does a better job at filling gaps and some people (like http://www.rpiv8.com) think the engine needs that weight. I still think the u-joints should be checked. It takes a load on them to make noises sometimes. The fact you don't hear the noise at a standstill and that the symptoms you report are consistent with mine and others' experiences add up. | ||
| Craig McLaughlin (Cmclaugh) Member Username: Cmclaugh Post Number: 51 Registered: 06-2002 |
I've taken the vehicle to a local mechanic I know and trust. He suggested pre-ignition as a possibility due to carbon deposits. Vehicle has been well maintained and has relatively low miles (65k) could this be the culprit? Besides tearing the heads off and scraping away all the build-up is there a non-invasive approach I could try first? | ||
| Geoff 93 RRC (Geoff) Member Username: Geoff Post Number: 119 Registered: 11-2002 |
It happens. My wife had a Mazda 626 v-6 a few years ago and had the problem with 50K miles. In that case it was caused by defective plug wires affecting combustion. No need to disassemble engine. Use chemicals. The best stuff is Sea Foam (NAPA among other places). Take out the sparkplugs and fill up the cylinders. Lightly replace plugs. Let sit overnight. Take plugs out in morning, crank motor to move any fluid out via spark plug holes. Replace plugs and run motor/drive vehicle at high rpm to help expel carbon. A second or easier treatment is to let the motor inhale Sea Foam using the vacuum line at the top of the plenum (at least in my case for the 3.9 motor). Run motor at about 1200 rpm to get good vacuum and it will suck it out nicely. 1 or 2 cans should do it. Make sure the motor is hot first for best results. An alternative to Sea Foam is GM top engine cleaner, available at any GM dealer (the Mazda guys used this). Use same way. Plain old water works too, kind of in a steam cleaning sense. I do the water treatment every now and then. Change oil after treatment. OK, uncle. Good luck. | ||
| Craig McLaughlin (Cmclaugh) Member Username: Cmclaugh Post Number: 52 Registered: 06-2002 |
Thanks for the info I'll give it a shot. Anything would be better than tearing the engine apart at this point. | ||
| Geoff 93 RRC (Geoff) Member Username: Geoff Post Number: 121 Registered: 11-2002 |
Sounds good. I'm not sure how familiar you are with aluminum heads, but be careful with the sparkplugs. Make sure the holes are free of debris and start the plugs by hand to avoid cross threading. Torque to 20Nm (verify that - not sure what the lb/ft equivalent is). Skip it if unsure and try the inhale method and let your mechanic do the soaking if that doesn't work. | ||
| Glen Hernandez (Polofella26) Member Username: Polofella26 Post Number: 58 Registered: 11-2002 |
I am having the same frigin problem. The noise only comes after the truck is warmed up and when I am either in reverse or when I accelerate. Its a loud ticking noise and I do believe that my exhaust is loose somewhere. It is not coming from the engine, however I have not gotten under the car to take a better look. | ||
| Craig McLaughlin (Cmclaugh) Member Username: Cmclaugh Post Number: 53 Registered: 06-2002 |
I will be having my local mechanic perform some ignition checks and fuel pressure checks on Monday. He also talked about checking the knock sensors to verify they are working properly. Basically he is going to look over anything that would contribute to incomplete fuel burn and the resulting carbon build up. He said it could be something as simple as the wrong type plug and/or bad ignition lead. You run the thing like that for a few thousand miles you are bound to have some carbon build up resulting in pre-ignition. Hopefully, I can get this resolved without tearing the heads off. | ||
| Glen Hernandez (Polofella26) Member Username: Polofella26 Post Number: 59 Registered: 11-2002 |
Let us know what he says Craig! | ||
| Edward Bibb (Heirless) New Member Username: Heirless Post Number: 30 Registered: 04-2003 |
you may summarize some of the suggestions you have heard on this board, and share this information with your mechanic. | ||
| Craig McLaughlin (Cmclaugh) Member Username: Cmclaugh Post Number: 54 Registered: 06-2002 |
Doing a little snooping around on my own this weekend I pulled two sparkplugs from each bank and noticed a bit of carbon build up on each plug. On a couple of the plugs you could see where carbon had built up to a point where it has flaked away during combustion. If that's what the plugs look like I'd hate to see inside the combustion chamber. Anyway, I put the plugs back without cleaning them so my local mechanic can take a look. It will be interesting to see what he determines as the source of the clattering. Praying for something cheap and simple. I can picture in my mind the LR service writers pen running out of ink as he prepares my repair order. I'll wager many a Discovery owner has second mortgage their home to repair an ailing friend. | ||
| carl J. Drumgoole (Carl_kps) Member Username: Carl_kps Post Number: 70 Registered: 02-2003 |
I have a low rumbling diesel sound too in my 01 Disco 2, with 80,000 miles on it. It only does it on mine when I accelerate. It a faint rumbling and I did not really think about it until one of my friends asked me about it. I have only used premium gas and have kept up with all of the warranty stuff. (I also changed my U-joints a bit ago and sound is still there). Any ideas? Hope its not carbon. | ||
| Craig McLaughlin (Cmclaugh) Member Username: Cmclaugh Post Number: 55 Registered: 06-2002 |
My local mechanic spent some time today diagnosing my clattering noise. He had several guys in the shop drive the vehicle on their own and report back on their findings. Each one felt the clattering was indeed pre-ignition and/or detonation due to carbon build up. Each said they noticed the noise more under heavy load at low rpm just before the transmission downshifts. They then pulled all the plugs and examined them carefully. Each plug had a fair amount of carbon build up. Surprised the hell out of me considering they were only replaced five months ago. On a few of the plugs you could see where the carbon has flaked away during combustion. My mechanic recommended I stay with either the stock LR plugs or a set of NGK's rather than the Bosch Plats I was using. He said Bosch plugs are good but he has encountered a few vehicles with drivability problems which magically went away after switching out the Plats. They also performed a MotorVac Carbon Cleaning on the fuel system. They ran the vehicle for about 35 minutes on the system to try and flush all the carbon out they could. They told me to drive at various road speeds and engine loads to help flush out the system as it may take a few days to see if the cleaning has workd properly. After about ten miles worth of driving back from the shop and around town I did notice the clattering has almost completely gone away. I'll drive the vehicle the rest of the week and see how she holds up. | ||
| carl J. Drumgoole (Carl_kps) Member Username: Carl_kps Post Number: 71 Registered: 02-2003 |
Its just a light diesel rumble. I can just barely hear it in mine. It is difinitely coming from the engine area and it is only during acceleration. Its very faint, like a slight sputter. Is the the problem you guys have? | ||
| Dave Harger (Orange) New Member Username: Orange Post Number: 1 Registered: 10-2003 |
I think I've got the same problem........ 99 Disco II with 80k miles. I dodn't know what to call it. After running some injector cleaner through the gas tank a time or two it got mildly better, but never really solved. I've read other posts about guys cleaning the plenum or the entire air intake system, can someone describe to me how to do this? I popped the hood last night and took off the air filter to see how it looked. When the engine was running it sounded as though the engine was starving for air, when I passed my hand over the air intake for just a second with the filter off the engine almost died. Is that normal? Dave  |
