Vibration / Noise at low RPM
Posted: Thu Nov 03, 2016 12:35 pm
So I'v been lurking on the forum since I bought my deli a year ago, and have been able to diagnose and solve many problems from all the great info here. So thanks for that! I have done a lot of searching and reading about various vibrations, rattles, knocks, and general diesel clatter, but have yet to be able to pin down the cause of my vibration. If a thread already exists please point me in the right direction. I've done some troubleshooting of my own and now I'm at a point were I really need another opinion from someone who knows their way around old diesels. I'll be getting my diesel mechanic to take a look soon but he is also new to delicas. Maybe this is totally a newb problem, Anyway here it goes:
The vibration occurs all the time at low rpm when idling or rolling slow around town and has done so since I've owned it. It gets a lot louder when on the accelerator. I mean any input at all, a slight touch and you get a grrrrr from under your butt. It all completely smooths out in the 1000-1500 range and higher. It's only maybe slightly better when she has been running for a while and is nice and warm. Specifically the sound is hard to describe, but it's enough to rattle loose change, the rear hatch, exhaust, parts of the interior, and is generally just loud inside the cabin. grrrrrrggrrggrrrr, it doesn't sound right.
I've mostly just ignored it because the van runs great otherwise. There is a decent amount of power (I can cruise at 125 on a flat with no wind) and is nice and smooth when the rpms are up. I'm starting to worry that it is the sign of some underlying problem that could bite me at the worst time. It would be nice to have the confidence from a nice sounding engine when i'm on a long trip.
Here is my troubleshooting thus far:
New air filter: got slightly more power in the high range from this, vibration persists.
New Oil filter: very noticeable increase in power, no change in vibration
engine mounts: I installed 4 new mounts, (two at the engine, and two at the back of transmission) there was no change in vibration. The mounts I pulled out were in poor shape however, so that's reassuring.
check belts: I went straight for the timing cover with the new thought that this is a combustion performance issue. Confirmed that all three(?) timing marks are lined up (they were) and reset the tension. I turned to the accessory belts, and one of the alternator belts is totally loose (this must be it!). I put two new belts on and re-tensioned the rest which looked fine. aannd.. no change in vibration and cabin noise! damn. Although an interesting note is that prior to the belt check the motor would visibly vibrate. You could grab the valve cover at idle and your whole arm would look all fuzzy. That is pretty much gone, but you can still feel it and hear it at the same level in the cabin. humm..
Installed a hydronic heater: The reason I did this was for cold starting and winter camping, but I want to note that I tee-ed into the fuel line pre-filter and the vibration possibly got worse but it's hard to tell because I am hyper focusing on this damn sound now. I can't remember what I considered normal. I wouldn't think that the tee would resist the fuel enough to make a difference (the heater isn't usually on when the engine is on so the injection pump is not competing with the heater pump. I also installed a check valve on the heater side to be sure). btw this type of heater incredibly worth the money and time to install if you live in the cold. I probably could post some pictures of my set up as it was a trick to find space for it.
fuel additives: I've tried many and even some injector cleaners. Not noticing much difference I settled for using Howes Diesel Treat or Power Service products.
I'm beginning to get into the realm of repair that I'm new to and will probably need some assistance with (diesel injection system). I don't want to go messing with the injection pump and screw things further. On the other hand, is it possible to make small injection pump adjustments without tearing things apart?
Some other possible causes I've read about :
alternator: A dying alternator can cause belt slip, which maybe explains why it will smooth out as the engine spins it up. I could likely get it rebuilt locally.
injectors: doesn't seem likely since it runs fine at higher rpm
injection pump: not providing enough pressure at low speed. or fuel delivery is off somehow
balance belt: not clear to me where/what this is
rocker arms: yikes
valve tuning: more yikes
Well thanks for getting to the end of my saga here, and I very much appreciate any tips in advance. It would be sweet if this is something I can fix myself (I'm pretty mechanical, but new to delicas and diesel in general). Trying to avoid a long trip to a delica mechanic.
1990 L300 automatic-4
4d56
209k km
Thanks
The vibration occurs all the time at low rpm when idling or rolling slow around town and has done so since I've owned it. It gets a lot louder when on the accelerator. I mean any input at all, a slight touch and you get a grrrrr from under your butt. It all completely smooths out in the 1000-1500 range and higher. It's only maybe slightly better when she has been running for a while and is nice and warm. Specifically the sound is hard to describe, but it's enough to rattle loose change, the rear hatch, exhaust, parts of the interior, and is generally just loud inside the cabin. grrrrrrggrrggrrrr, it doesn't sound right.
I've mostly just ignored it because the van runs great otherwise. There is a decent amount of power (I can cruise at 125 on a flat with no wind) and is nice and smooth when the rpms are up. I'm starting to worry that it is the sign of some underlying problem that could bite me at the worst time. It would be nice to have the confidence from a nice sounding engine when i'm on a long trip.
Here is my troubleshooting thus far:
New air filter: got slightly more power in the high range from this, vibration persists.
New Oil filter: very noticeable increase in power, no change in vibration
engine mounts: I installed 4 new mounts, (two at the engine, and two at the back of transmission) there was no change in vibration. The mounts I pulled out were in poor shape however, so that's reassuring.
check belts: I went straight for the timing cover with the new thought that this is a combustion performance issue. Confirmed that all three(?) timing marks are lined up (they were) and reset the tension. I turned to the accessory belts, and one of the alternator belts is totally loose (this must be it!). I put two new belts on and re-tensioned the rest which looked fine. aannd.. no change in vibration and cabin noise! damn. Although an interesting note is that prior to the belt check the motor would visibly vibrate. You could grab the valve cover at idle and your whole arm would look all fuzzy. That is pretty much gone, but you can still feel it and hear it at the same level in the cabin. humm..
Installed a hydronic heater: The reason I did this was for cold starting and winter camping, but I want to note that I tee-ed into the fuel line pre-filter and the vibration possibly got worse but it's hard to tell because I am hyper focusing on this damn sound now. I can't remember what I considered normal. I wouldn't think that the tee would resist the fuel enough to make a difference (the heater isn't usually on when the engine is on so the injection pump is not competing with the heater pump. I also installed a check valve on the heater side to be sure). btw this type of heater incredibly worth the money and time to install if you live in the cold. I probably could post some pictures of my set up as it was a trick to find space for it.
fuel additives: I've tried many and even some injector cleaners. Not noticing much difference I settled for using Howes Diesel Treat or Power Service products.
I'm beginning to get into the realm of repair that I'm new to and will probably need some assistance with (diesel injection system). I don't want to go messing with the injection pump and screw things further. On the other hand, is it possible to make small injection pump adjustments without tearing things apart?
Some other possible causes I've read about :
alternator: A dying alternator can cause belt slip, which maybe explains why it will smooth out as the engine spins it up. I could likely get it rebuilt locally.
injectors: doesn't seem likely since it runs fine at higher rpm
injection pump: not providing enough pressure at low speed. or fuel delivery is off somehow
balance belt: not clear to me where/what this is
rocker arms: yikes
valve tuning: more yikes
Well thanks for getting to the end of my saga here, and I very much appreciate any tips in advance. It would be sweet if this is something I can fix myself (I'm pretty mechanical, but new to delicas and diesel in general). Trying to avoid a long trip to a delica mechanic.
1990 L300 automatic-4
4d56
209k km
Thanks