Howdy.

Looking for a little help from guys with more experience with these engines. I've searched the 'net but haven't found anything which addresses a specific condition I've noticed related to this noise.

Background:
1981 300SD starts and runs well. Purchased short time ago, noise came with engine. No maintenance records. Engine seems to have been maintained well over it's life i.e. very little apparent "hack work" or shortcuts. However I was told that it sat in a garage for "a while" and wasn't driven before being obtained by previous owner and there are signs this is true. PO had car for a short time as first vehicle then moved up to newer model. I've been a tech for 20 years primarily with gas engines and some light duty diesel truck stuff and up until about a month ago, was driving an '82 300SD until it got too rusty to keep on the road.

The noise:
Loud "click" or "tick" type noise as opposed to "knock" or "bang." Frequency seems similar to single combustion event. Occurence doesn't depend on trans in or out of gear. During pre-purchase inspection I listened with screwdriver on block, heads, valve cover, front of engine, vacuum pump, and really couldn't locate it. I certainly never felt a disturbance through the block while checking (use the force, Luke) like one might with a bearing failure so I decided to buy it.

Noise is loud. Loud enough that people on the sidewalk stopped to stare at the car while I drove by one day. PO drove it about 3k miles and reported the noise was there in the beginning and it never changed. PO's uncle was a mechanic and he said he never noticed any change in the noise. Under car, again with screwdriver to engine, seemed like noise might be strongest in center of block area but nothing jumps out as definite. Noise sounds somewhat like rod knocking noises on yootube videos but disabling each injector individually does not isolate or change noise. Noise is not combustion related as shutting engine off in gear while car is rolling didn't change tone or sound. Balancer appears to be intact and all pulleys on front of engine seem to be in place and not hitting anything.

Unique symptom:
Last night I discovered that noise will stop if nose of car is oriented uphill. It takes a short time for the change to occur. If the car is oriented downhill immediately afterward then the noise will return, again after a short time has passed.

Questions:

Does this problem sound like something someone has run across? The fact that the noise stops with the nose of the crank higher should be pretty telling.

The car seems to have low vacuum. If the pump is failing mechanically and making noise, is it common not to feel it right at the pump?

If a timing chain related part such as a guide or tensioner is causing this noise, wouldn't the frequency of the rattle be higher, related to speed changes of the crank and cam?

The uphill / downhill issue suggests a thrust bearing on a shaft may be at fault. As the shaft walks forward the noise could stop but when the shaft moves toward the rear of the block there's some contact somewhere. Anyone run into this one? A bad thrust bearing is one type of failure that could allow the engine to be driven a long time without a major failure.

On some of the vehicles I've worked on over the years I've been able to asses total play in the timing chain system (chain plus tensioner and all guides) by measuring the amount of cam rotation back and forth before the chain becomes taught on either side. Does anyone have a guideline or rule of thumb I can use for this? We're not talking chain stretch, but a means to asses chain plus related parts without disassembly.

I'm currently stripping the '82. In fact, as soon as I finish typing I have to get back to it. The IP is out and so is the vacuum pump. I've pulled the low mileage timing chain as well. Should I keep the IP timing device as well, just in case it's related to this noise?

The amount of time I can get in the shop is limited and availability can be very random so I'm hoping to narrow down as many possibilities as I can before pulling the engine apart. It runs well and I'll do what I have to for a repair but I really don't want to end up pulling the entire engine for major disassembly just to do an inspection. The car's in the shop now and I plan to try and determine if there's excessive crank end play before I leave.

Tried to cover as much as I could based on questions frequently asked by troubleshooters. I've used most of the tricks I know to isolate this but no luck so far.

Thanks in advance.

bump

__________________
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My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
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Sounds like it could be the vac pump. Failure of it can mean breaking the timing chain, and that gets expensive fast, so its nothing to fool around with. If you have a parts car with a known good pump I would change it out.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Therefore, it's not engine related and it's not a vacuum pump.

Clearly, something on the front end, probably one of the bearings, is in need of replacement.

Is the frequency of the noise related to the speed of the vehicle?

Does the noise disappear on heavy braking?

The vacuum pump is definitely worth checking but as you said that you felt the noise was coming from the middle of the block somewhere (and not necessarily the vacuum pump) my vote would be to check out the end play on the intermediate shaft.

The vacuum pump runs on this roller coaster track that has the effect of creating a longitudinal shimmy that pushes the timing device (said track is on timing device) up against some (bronze-like?) bushings and the intermediate shaft (that then connects to the IP.

There's a limit of end play for this shaft of 0.05 - 0.012 mm (see chapter 07-240 in the FSM - FSM can be got on a good day for free via www.startekinfo.com)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

@Brian

My impression was that the car was stationary when this was done.

@1project2many can you confirm whether the car was stationary at this time or not please?

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Did you miss the statement "while car is rolling"?

But the engine would still be turning so I think it is engine related. And, I assume the noise occurs while the car is stopped since he mentions the noise going away with the car facing uphill. I'm thinking it may have something to do with the vacuum pump also.

Can the engine be started and run with the vacuum pump removed?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Yes. I've run a 617 out of a vehicle with the VP removed with no issues. As the oil warms up, it will spray a mist from the pump opening.

__________________
'83 300D, 126K miles.

Then that's what I would do. Pull the pump, start the engine and see if the noise goes away.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I'd be curious about that............

Will the trans drive the engine to sufficient speed so that the sound level and frequency of the noise doesn't change?

Not sure but the rear pump on the transmission locks up the transmission to the engine enough to get the car started. Will it keep it turning at higher rpms??????

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Nose up might keep the crankshaft settled down if it has too much end play. I was even speculating on a cracked crank. How does the engine sound nose down?

With your experience I suspect you can determine well enough that it is or is not occuring in the vacuum pump area.

In looking at the vac pump as the symptom ,a failure of this piece is usually the armature that holds the bearing ,pieces of metal will fall into the motor with not a good outcome .In my case I was lucky ,didnt seem to find its way into any harm but was still worried of were those small pieces went.It was a 190d and I drove that car for some yrs after the event.I dont know if it could be nailing that your having ,it would be an easy fix if it was a forward injector acting up.
Not out of the question ,I was once told a noise problem was found by accident ,the mechanic found a nut that had fallen was caught up around the crankshaft pulley ,noise kept coming and going and gave them a fitt trying to dignoosseo.
Funny story I heard last week ,2 mechanics were always pranking each other ,one had just finished a major overhaul and was getting ready to fire it up ,meanwhile the other mechanic would slide underneath the car with a hammer and ding the under carriage at a steady pace when the car was running ,the mechanic would start then stop ,messed with something else under the hood while cursing ,start it again ,walk around a bit ,look back at it again,curses got louder and louder ,this went on for 30 minutes until the mechanic starting throwing tools around ,he fessed up to his evil doings and the car went out the same day .

Thanks for the replies. These are quick answers as I don't have much time at the pc right now.

Car was coasting downhill in gear and I shut key off. Rear pump in trans generates enough pressure to maintain clutch engagement. End result is engine turns but fuel is not injected for a brief time (can't comment on what happens if vacuum bleeds away from fuel shutoff). Sound is engine related, but doesn't change when combustion is removed (sometimes bearings, piston pins or piston slap can be diagnosed by this method as it's worse when engine is running).

Last night I pointed car downhill in driveway and let it run while listening for noises. While I wasn't able to pinpoint a specific noise, I did come away with a ringing ear after listening at the top of the head in the area of the timing chain tensioner. I also noticed that I hear a fair amount of noise at the forward end of the vacuum pump but much less in the "bell" shaped area near the engine attaching surface.

I'm going to pull the valve cover and vacuum pump for a visual inspection. I think it would be a sad statement if I allowed this engine to die because I didn't check these parts, especially given frequency of failure and the distinct lack of records.

But still listening for suggestions or tidbits.