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[Kaitsu]

Sometimes, sometimes not...
Knocking sound from driver side, sometimes when idling with gear on (th200r4) or when driving light throttle. I checked valve springs, can't see anything wrong.And I couldn't find anything what makes noise. Easier to hear it outside car than under hood.
Converter bolts tight.

Frequency..hmmm..difficult to say is it from piston or valves??

It has no effect running engine,rpm etc., just a sound what sometimes makes wonder.
What if oil pressure low => lifter problem,roller?
If there is problem with piston, bearings etc., why it's not heard all the time?!

Question: What clearance has push rod to rocker arm? Because it can't be adjusted like gas engines, can you rotate rod by fingers or???
Injectors were rebuilted on May. This sound was heard also then so it didn't make change.
Engine (rebuilted) is ~70k driven (year -85 model).

What possibly can break if you start engine after given fuel via intake manifold?
I know it must not be done that way but if...?

[britannic]

A quick way to help with pin-pointing the knock:

Is it half engine speed? If so, then it's likely to be somewhere in the valve/cam train. Full engine speed will be most components connected to the crankshaft.

Use a mechanic's stethoscope or long screwdriver to listen to the engine and try to pinpoint it. I had a half speed knock that didn't vary under load, only with engine rpm and it turned out to be a bad lifter.

The lifters only pressurize and remove the pushrod play when the engine is running, so don't worry about being able to spin the pushrods by hand.

Feeding fuel into the engine via the intake, may lead to hydrostatic locking (one cylinder received more than the rest), blow back or a runaway engine the revs itself to destruction as the fuel builds up in the manifold and gets suddenly gulped later.

[Kaitsu]

Thanks britannic!

Yes it sounds to be rpm or low rpm problem.

Okay, I can rotate rod but there should not be any gap??

If I take valve cover off and look for oil coming from rods...when idling and if there is seen difference how oil comes up...bad lifter?? Hmmm...maybe no.

Ok, I really need to try locate the sound.
There is so much sound under hood...heh!! :confused:
Is it impossible to take out lifters without removing head?
Lifter cost 15$/pcs.

[britannic]

The lifter takes up the slack in the pushrod to rocker clearance using engine oil as a hydraulic fluid. A worn or damaged lifter collapses and eventually won't lift the pushrod enough to actually work the valve - there will be a misfire as well as noise associated with this.

First make sure the knock/clack is at half engine speed.

If it is, then use a screwdriver to pinpoint which head/cylinder it's coming from. If you're going to replace all of the lifters at the same time, you don't need to worry too much.

It's possible to remove the lifters without taking the head off. You'll need a great deal of patience, a mirror, magnetic pickups, long screwdriver etc.

With the rocker covers, rocker assemblies and pushrods removed, unbolt the lifter retainer plates and use the mag pickup to pull them out of the tappet chests.

Now use the mag pickup through the pushrod holes and main tappet chest slots to pull the lifters out.

Replacement is more tricky using the mag pick up/screwdriver combo, since not only will you have to maneuver the lifter into the lifter hole, but you will also need to align them so that the retainer plate fits properly. It's possible to bolt the retainer plate over misaligned lifters and destroy them within a few miles.

It's definitely doable without taking the heads off and I've done it twice now using this method - just don't rush it :D .

[Kaitsu]

I'll go slowly with patience.

Example 1, when I stop to traffic lights with hot engine, keep window open, SOMETIMES I hear clearly knocking sound at 650rpm, but it may change it's frequency or it's not heard all the time making the sound like machine gun. Like something would be loose...this is very difficult to explain.
Other times it "idless" like a cat :D

Example 2, driving 20mph with big gear and light throttle (~1000rpm) to small uphill, same knocking can be heard (you can't hear it inside car if window closed)


First I try to locate sound before taking any parts off.
Mechanic stethoscope could possibly help...
If lifter/cam is bad, would it be seen /heard when valve cover off?
Can broken valve spring make knock sound?
Again, why it's not all the time :confused:

Any other hints what could make knocking randomly?
Especially 'cause it's not effecting anyhow to engine run (no misfires, no bad rough running etc.)
Well, weekend comes...work starts.

[ 10-15-2003, 10:28 AM: Message edited by: Kaitsu ]

[Kadzban]

I was into Peninsular Diesel the other day replacing my CDR, passenger valve cover and oil fill tube with stuff from a 6.5. Just so happens Peninsular is in town.

Anyway they had a 6.5 engine in there that was knocking and it was an injector. He said it was the usual cause for knocking.

I'd try running it hard on hills to clean the injectors a little. My old truck seems to run better after such a work out. If the noise goes away after this. Then comes back a day or 2 later. I'd maybe lean towards an injector.

HTH
Good Luck!

[gmctd]

Have you inspected the harmonic balancer and isolated accessory drive pulley?
When badly deteriorated, they knock in the manner you relate.
And, as Jared suggested, a weak injector can cause a rod to sound off.

jd

[Kaitsu]

Hmmm... that I haven't checked.
I've read articles of it here in DP.

If injector is leaking, it should be possible to locate sound (with mechanic stethoscope) close to the injector?!

Thanks!

[gmctd]

Yes, that is a good method for locating intermittent noises. The discerning ear can sense differences in injection pulses with a good stethoscope.
A long screwdriver will get the job done, as Brittanic can testify.

jd

[crew84]

I had the injector knock problem. If it will knock at idle then just loosen one injector fuel line nut at the injector at a time while it is running and listen. Retighten each one as you go. When you reach the one that is knocking the noise will stop. Of course if it is a cracked piston it will stop also. Then you will have to try another new injector in its place to find that out.

[rumbler1]

Kaitsu, I had a strange sound a while ago that was similar to yours. I had a tapping noise that I not only heard, but could feel coming through the gas pedal. It only occured when the engine was warm and sounded like it was in the engine. I looked it over a few times and couldn't find anything wrong. I was getting frustrated when one day I happened to be underneath the truck on the driver's side and noticed that my oil cooling lines were extremely close to the cab at one point. I did some "body work" on the cab at that point and the noise went away. It seems that under the right conditions the lines were hitting the cab and translating the contact through the floor and gas pedal. This may not have anything to do with your situation, but it might be worth a look. Good luck.

[Kaitsu]

Thanks, you all are giving me good tips smile.gif

Simple questions:
- why would a bad injector make tapping noise?
- cracked...how? What other things would be seen / heard if cracked...??
Cylinder pressure test should be done...

Well, there's a lot to do so "I'll be back..."

BR, Kaitsu

[britannic]

Injector components are subjected to pressures approaching 1 ton per square inch or more. Unsecured injector lines, damaged pintles etc., can produce noise out of all proportion to the movement involved. Imagine being able to wield a 1 ton hammer the size of a pin (strong enough not to bend or break) and then tapping it on metal by moving it a 0.01-0.5mm very quickly - the noise would be very impressive!

Before we lost most of the messages on this forum, there were some threads describing injector knock, that sounded just like a connecting rod big end hammering itself to destruction.

[78Chev]

Kaitsu:
My knock/tick (pretty loud, especially when warm) turned out to be my vacuum pod. The pod itself was not defective (I replaced it with new) but something was clacking where it connects to the hex driveshaft that turns the oil pump. I put a stub in its place and it does not make that aweful noise now. I found the noise by using a stethoscope and by swapping in the stub. I just recently put in a Volvo electric vacuum pump to run my A/C doors and I'm much happier now. As with yours the knock/tick did not affect engine performance but did drive me nuts. Something to check out at least.
Randy

[britannic]

Originally posted by 78Chev:
Kaitsu:
My knock/tick (pretty loud, especially when warm) turned out to be my vacuum pod. The pod itself was not defective (I replaced it with new) but something was clacking where it connects to the hex driveshaft that turns the oil pump. I put a stub in its place and it does not make that aweful noise now. I found the noise by using a stethoscope and by swapping in the stub. I just recently put in a Volvo electric vacuum pump to run my A/C doors and I'm much happier now. As with yours the knock/tick did not affect engine performance but did drive me nuts. Something to check out at least.
Randy 78Chev: Do you have a part number for the stub that you used to replace the vacuum pump please?

[mhagie]

78chev, where did you find the volvo electric vac pump?


Brittanic, the # on my stub w/ess is as found on top of unit 7841996 mine is a 93 or 94 ESS.

[78Chev]

mhagie:
I went to a Volvo-only used parts place in Portland Oregon. They supposedly had three but could only find one when I was there. Paid $20 for one in perfect condition. I can get the part number off of it if you are interested. The thing generates about -22 inches Hg in the vacuum reservoir in about 10 seconds. I can check the part number on the stub later today or tomorrow for you.

I'm also looking for a normally-closed vacuum switch that opens contacts at about -20 inches Hg to automatically operate the thing. Any suggestions where to get one? Thanks.
Randy

[Kaitsu]

Originally posted by 78Chev:
Kaitsu:
My knock/tick (pretty loud, especially when warm) turned out to be my vacuum pod. The pod itself was not defective (I replaced it with new) but something was clacking where it connects to the hex driveshaft that turns the oil pump. I put a stub in its place and it does not make that aweful noise now. I found the noise by using a stethoscope and by swapping in the stub. I just recently put in a Volvo electric vacuum pump to run my A/C doors and I'm much happier now. As with yours the knock/tick did not affect engine performance but did drive me nuts. Something to check out at least.
Randy Sorry my questions... what is POD? :rolleyes:
Is it vacuum pump's part or...?
Mine has now belt driven, but there is blocked hole in position where originally has been vac.pump. You mean something down there close to the oil pump axle or?
Oil pan off to check it or?

I didn't get mechanical stethoscope, I bought 1 meter long 10mm metal bar and tried to hear...%

[catmandoo]

have you checked flywheel and converter bolts.

[78Chev]

Kaitsu:
If you have a belt-driven vacuum pump instead of the vacuum pod at the back of the engine, then this will not be the source of your knock. When I took my vacuum pod out and put a stub in (like you have back there) my tick/knock went away. Good luck.
Randy

[Kaitsu]

Yes...now it went to my head tongue.gif

Flywheel and converter bolts are tight.
What if damper is bad? Random knock or?

This knocking is a pain...
When you try to hear it, it's off and when you drive light throttle...it can be heard easily.

Like today, when I got home it was so nice diesel idle without any extra noise :rolleyes:
I should take damper off and try to see if it has any sign to be bad.

It's been now about 6 months and still running...

-How easy it would be if I had a garage-

CAN a bad DB-2 make such thing to injector(s) what would be heard as knocking sound??

Just wondered, my engine smoking started somewhere 6 months ago :confused:
Pump has something internal problem because it started to smoke and smell unburned fuel and I had to turn fuel screw 1/4 turn down...
Activating HPCA does not make difference almost at all (even hot).

More knowledge, more pain ;)

[ 10-27-2003, 08:34 AM: Message edited by: Kaitsu ]