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Author Topic: Diesel knock? - NOW FIXED!!!!!!!  (Read 10299 times)
regcheeseman
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« on: March 14, 2011, 04:12:44 AM »

I sold an engine to a friend for his caddy and gave him help setting it up.

It knocks quite heavily  Roll Eyes

I changed the pump timing and still the knock remained, I even swung the pump across it's timing limits while the engine was running - no real change.

He swapped the injectors for known good ones - still knocking.

Fearing the worst I missed out on Sunday lie in and was down at his garage early, I pulled the head - very clean, slight carbon build up on number 3 but as expected.

Now pulled the sump, nothing in the oil, dropped the connecting rod caps and pulled the pistons out to check

Still nothing  Huh?

It's not lifters as it's not 'that' type of ticky noise, it's more clack.


Any ideas people? It starts and runs fine. Just noisy.

It can only be pump now surely?

« Last Edit: May 26, 2011, 01:43:47 AM by regcheeseman » Logged
8v-of-fury
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« Reply #1 on: March 14, 2011, 04:38:15 AM »

Diesels do have a particular knock to them all the time, to the tune of an explosion happening in the piston at 23.5:1 compression. :p

however, if you say it is louder than normal, and you have checked everything.... I dunno what is left. I had a set of dirty injectors run all stupid.. and loud. ATF fixed the knock.  you have swapped the injectors so maybe there is something in the pump.. Do you have it back together in running order? I'd get it back together and run it off a bottle of Auto Trans Fluid.. let it fill the pump and let it sit over night (in a heated garage, atf doesnt like to start cold) and then run the piss out of it the next day, and see if it helps! 
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Bugsy_malone 666
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« Reply #2 on: March 14, 2011, 04:48:37 AM »

I noticed when my diesel was cold the other day it has a much more industrial clatter/knocking noise, but I know full well its just the sound of the diesel engine when cold.

Did you warm it right up first?
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regcheeseman
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« Reply #3 on: March 14, 2011, 05:02:48 AM »

It's not normal knock - it's pretty damn loud. I do appreciate a normal cold IDI diesel engine is noisy but this is +30% extra.

It 'seems' to be coming from the engine rather than the pump - as if a pump setting/problem is causing the knock rather than anything physical within the pump. Hard to tell though.

I just wanted to be sure I'd eliminated the possibilites before I fit the head back on.

I did notice that the owner is running a single central speaker with a 6x4 speaker - maybe this needs to be upgraded?
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Bugsy_malone 666
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« Reply #4 on: March 14, 2011, 05:39:38 AM »

I did notice that the owner is running a single central speaker with a 6x4 speaker - maybe this needs to be upgraded?

Ah theres your problem right there, bigger speakers = less ability to hear the engine :lol:

I honestly dont know why it could be knocking, its not something like the brake vacuum pump or something related to the intermediat shaft is it? How about clutch/flywheel? If they werent fitted tight enough might do it.

I think really you should probably get an oil pressure gauge hooked up and try to determine if theres a problem with oil pressure as to why it could be knocking.

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regcheeseman
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« Reply #5 on: March 14, 2011, 06:29:44 AM »

Funny you mention clutch/flywheel and somehow the TDC mark is about 45 degrees away from actual TDC.  Huh?

Yes it IS a diesel flywheel and clutch.
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Bugsy_malone 666
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« Reply #6 on: March 14, 2011, 06:53:50 AM »

Well the reason I mention about the flywheel/clutch is because of a problem I had when I was fitting a new engine to a T25 working for my Mechanic mate, basically we got the new engine and stock the old flywheel and bolts in, after a few hundred miles apparently it started knocking really bad and we were a bit worried as it was a Vega Recon with the temperature guarentee sticker on it, turns out when you fit the flywheel your supposed to use new bolts! Now I know why this is and when I did the diesel in my Camper I used the same bolts, but used lock tight on them and did them up to book spec. After several thousand miles I have had no trouble, but I know when you take the old ones out they have some blue lock tight on them which is why they say 'new' bolts when refitting the flywheel.

The other thing I found with the clutch arrangement is that you can fit the flywheel 1 way only if its the flywheel that bolts to the crank, in which case the clutch pressure plate has the markings on and I think it can be fitted atl east 1 of 3 ways, when you have the pressure plate that bolts to the engine, that only fits one way round, but I think you have the make on the flywheel that can be fitted one of 3 or 6 ways round (which would account for it being maybe 45deg out.)

Depending on if the engine already had the clutch fitted or not I guess that would have been the first thing I would have checked before ripping the rest of the engine apart.
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clarkrep
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« Reply #7 on: March 14, 2011, 01:22:12 PM »

X2 on the flywheel bolts being loose.
Didnt put loctite on them one time, I did torque them though. I was 15 at the time an had just did a full engine rebuilt(my first Vw diesel) in my dad's caddy and after maybe a 100 miles they worked loose. I was VERY relived to find it being just that  Smiley
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'79 Rabbit Diesel L 1.5
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Vitwagen
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« Reply #8 on: March 14, 2011, 03:03:55 PM »

I had an AAZ that had a phenominal knock:

http://www.youtube.com/watch?v=uL3zUyLKwyU

Just found out this weekend what it was - does it sound anything like that?

I assume this is an AAZ fitted to a Caddy? originally a 1.6D?...
« Last Edit: March 14, 2011, 03:13:51 PM by Vitwagen » Logged
blackdogvan
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« Reply #9 on: March 14, 2011, 03:23:35 PM »

I've found the best way to differentiate knock from a fuel related clatter is a long hill, some speed & a downshift. With little to no fuel injected all you're hearing is the engine rotating & if its fuel related it'll be gone & if its some other nasty issue it will likely still be there.
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regcheeseman
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« Reply #10 on: March 14, 2011, 04:05:21 PM »

Quote
Depending on if the engine already had the clutch fitted or not I guess that would have been the first thing I would have checked before ripping the rest of the engine apart.

The engine is still fitted, ripped apart in situ. I can get to the back of the fly and 'shake' test it.
It did start the knock straight after fitting motor, so not sure the flywheel bolts could have worked loose instantly?


Vitwagen - it sounds a lot like that.....a replacement pump would be good Wink

It's a 1.6 TD fitted into a caddy mk1 that was 1.6D

The owner has noticed machining marks that look like a block skim - I've asked him to measure protrusion, it was running a 3 notch - could this potentially make it knock? There is no physical interference.
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Vitwagen
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« Reply #11 on: March 15, 2011, 10:21:03 AM »

Vitwagen - it sounds a lot like that.....a replacement pump would be good Wink

It's a 1.6 TD fitted into a caddy mk1 that was 1.6D


Ah, 1.6? My noise was an AAZ conrod cap hitting the 1.6 oil pickup pipe flange (!). The problem came about due to the longer stroke of the 1.9.

Pump needed eh? I expect demand on them may push the price up?  Wink
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79rabbit4dr
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« Reply #12 on: March 15, 2011, 07:01:01 PM »

http://www.google.com/#q=mechanics+stethoscope&hl=en&prmd=ivns&source=univ&tbs=shop:1&tbo=u&sa=X&ei=0yaATaqCKIaosAP4k-z5BQ&sqi=2&ved=0CCwQrQQ&biw=1366&bih=575&bav=on.2,or.r_gc.r_pw.&fp=d57722a22572de1d
I've had good luck narrowing down knocks (especially in extra noisy engine compartments with these) with one of these. Cheap for how useful it is. Just thinking outside the box.
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Paul
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1979 Rabbit 4dr Gasser - For Parts
1981 Rabbit 4dr Diesel - For Parts
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regcheeseman
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« Reply #13 on: March 16, 2011, 02:19:01 AM »

I've got a long screwdriver. Wink
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carrizog60
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« Reply #14 on: March 16, 2011, 05:16:21 AM »

on my gtd when the bushing on the accelarator shaft on pump went bad the engine will know badly... Huh?
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