Engine noise when warm

Edward George · Apr 23, 2020

I’ve recently bought a 1968 Series 2A with a Series 3, 5 bearing 2.25 diesel fitted. The previous owner had recently carried out a comprehensive engine rebuild with new pistons, shells and fitted an overhauled injector pump and injectors. As the engine gets warm, a metallic tapping noise suddenly appears and is then heard at all engine speeds. It occurs on acceleration, at steady speed and on the over-run. On restarting the engine from cold, the noise cannot again be heard until the engine has warmed up. Any suggestions as to what may be causing this? I’ve attached a recording.

Flossie · Apr 23, 2020

Wrong, too thin oil?

tottot · Apr 23, 2020

Plus one on the above. Worth checking tappets. Any difference with clutch in? See if you can work out where noise is coming from, front, rear, top or bottom of motor.

Wildefalcon · Apr 23, 2020

Loose hot spots?
A mechanics stethoscope is really useful to narrow down the location of noises.
The cheap ones are fine.

steve2286w · Apr 23, 2020

Did you attach anything , peeps before have put it on sound analyser to work out frequency which will help pinpoint cause

kermit_rr · Apr 23, 2020

Is it just me that can't see any attachments?

Flossie · Apr 23, 2020

kermit_rr said:
Is it just me that can't see any attachments?

Nope, me neither.
It's going tap tap tap tap when it's ticking over then
Taptaptaptaptaptap when revved up a bit I guess

Colthebrummie · Apr 24, 2020

Did the previous owner change the cam followers when he rebuilt the engine?

Col

Edward George · Apr 25, 2020

Thank you all for the much appreciated suggestions. I will follow up on all of these and let you know how I get on. It will probably be Monday though. I did wonder whether the attachment had taken properly. I took a recording of the metallic regular tapping noise with my iPad using the video camera feature. When I tried to attach it to my post it seemed to download correctly onto the post but I then couldn’t see an icon to play it back. Perhaps the type of file from my iPad is the issue? I’ll take another look at this also. It is strange that it happens only after the engine has heated up. It sounds as if something is top end is hitting the cylinder head or a valve but I will try to pinpoint with a sounding bar. I think the oil type and level is ok but I’ll check. I don’t think it is affected by dipping the clutch but will check this also. Also I’ll take off the rocker cover and check tappets and clearances. I don’t think the cam followers were replaced. I fitted an electronic oil pressure gauge on Thursday and am getting about 50psi at fast idle when hot which seems ok. Someone I played the recording to suggested it might be an injector spray pattern issue but it sounds too metallic a noise to me for it to be that. I also cracked each injector in turn and the effect on idle speed and roughness of running seemed the same each time. I couldn’t hear if the tapping noise was affected by this but could retry.

Edward George · Apr 25, 2020

I’ve managed to email the sound recording to myself from my iPad as a .mov attachment and can replay this successfully on my PC using Media Player. I don’t seem to be able to change the file type though to one accepted by the forum software. My email address is [email protected] and if you would like to email me requesting this attachment, I will send it. Thanks.

steve2286w · Apr 25, 2020

Edward George said:
Someone I played the recording to suggested it might be an injector spray pattern issue but it sounds too metallic a noise to me for it to be that. I also cracked each injector in turn and the effect on idle speed and roughness of running seemed the same each time. I couldn’t hear if the tapping noise was affected by this but could retry.

that could be a good guess,(diesel knock) but I think you would notice the difference when the pipe was cracked off
I had that and didn’t have the spray pattern in the manual, more a knock than a tap on mine,
You can remove injector and connect it up , crack off others so engine won’t start and check spray pattern
I recently took my 200tdi injectors apart to clean them in a cheap ultrasonic cleaner
Below some tips on noise from Haynes manual
YOU TUBE works well upload to u tube and copy the link

Colthebrummie · Apr 26, 2020

When you check the tappets, look at the amount of thread showing above the adjuster nuts, there should be roughly the same amount. If not, it might be a sign that a follower or two may be worn.

Col

Blackburn · Apr 26, 2020

When checking the tappets look at the inside of the rocker cover if the head has been skimmed it is possible for tappet adjuster to be hitting the cover.

Edward George · Apr 26, 2020

Thanks for the further suggestions on things to check out. I’ve ordered a mechanics stethoscope and have copied the audio of the knocking noise onto You Tube. Hopefully this link will work But this is all new technology to me.
if it doesn’t, please search on ‘1968 Series 2A engine knock (audio only)’

jamesmartin · Apr 26, 2020

dont bother with the stethoscope get the rocker cover off

steve2286w · Apr 26, 2020

Does not sound like the diesel knock I had , sounds more like a tappety noise. as above check the gaps using rule of nine
If you remove cover check by hand no loose rocker nuts , then run it And check all valve rockers moving the same then check gaps using rule of nine
Gaps 0.010 inch or 0.25mm with feeler

Edward George · Apr 27, 2020

Thanks for the further comments. I took the rocker cover off today. Didn’t affect the tapping sound and no sign of an adjuster hitting the cover, although a couple of the adjusters are showing more threads above the lock nuts than the others (about 1/4 inch difference) which is strange. Using the rule of 9 I checked the gaps were all about 10 thou and all pushrods were spinning freely with a good oil supply. Looking at the engine rebuild notes, as well as a complete new rocker shaft assembly, the valves and seats were refaced. Perhaps a couple needed extra work. I’ll try to compare valve stem heights. I’m wondering if some cam rollers or slides might be worn or damaged, though I’d have expected anything else worn to be replaced during the rebuild. At £34 a set from Turner Engineering plus having to remove the head again to do the work it’s not a happy prospect.

I have access to an injector spray pattern and pressure tester so I might do an injector compare to discount a malfunctioning one. My stethoscope should arrive any day now to help me pinpoint the source of the tapping. The oil is dirty but otherwise seems of the right viscosity. I have both straight 30 and 20/50 in stock so could try an oil change to see if that quietens things down.
Any further suggestions meantime would be welcome.

steve2286w · Apr 27, 2020

Just looking at first post , when cold revving no tapping?
a quick eliminator is slacken off belt to stop alt and water pump turning
Just wondering if bad seal on injector ie faulty copper washer near injector nozzle
No leaks around head gasket
Can you see much with side covers off ie cam flat spots

Edward George · Apr 28, 2020

Thanks steve2286w I haven’t checked that the injector locating nuts are tight to ensure the copper washers are properly compressed. I will do this next time. If I take the injectors out for testing, I’ll re-anneal or renew the washers to ensure a good seal. I’ll also slacken the fan belt to eliminate the dynamo and water pump. I haven’t done any investigation to date of the cam rollers or slides. When I get the stethoscope I’ll use an old feeler to slip under each rocker in turn to see if the tapping noise changes.

Edward George · Jun 2, 2020

After a lot more trial and error, I finally managed to sort the issue. With the stethoscope against number 4 injector the tapping sound was loudest. I took out the injector and found bits of carbon stuck to the area around the nozzle jet. When I bought the Landy, it had been run for a long time with the timing retarded (lots of white smoke) which had probably contributed to the build-up of carbon. As I didn’t have access to my injector test equipment due to lockdown, I purchased and fitted a reconditioned injector and the tapping noise was gone. Many thanks to everyone who made suggestions and helped me to find the solution.
Edward

Engine noise when warm

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