Knocking sound from intake after replacing head

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Mario110

Active Member
Posts
105
Location
Germany
Hi TD5 Experts,

I've bought a TD5 15P Engine (MY2002) with diesel in oil (190.000km). First, i have replaced the seals/rings of the injectors but without success - after some kilometres there was again diesel in the oil circulation system. When I've made the oil change, I've found some metal parts. I've found out that the car got a new turbo one year ago, so the metal parts are definitely from a broken turbo.
I've replaced cylinder head with a new one. I've also had the injectors checked, with the result that all have to be reconditioned. Not happy about this result, but I've agreed to recondition them. The chain tensioner was also replaced with a new one type LHP000080 - not sure if this is the right one (spare-part dealer said this type should fit).
Putting all together, the engine starts after a minute again, checking oil and water and I've started a small test drive with my mechanic (only some kilometres). And now the real problems are starting!

On idle speed, there was a ticking sound coming from valve cover and knocking sound coming from the intake. I've measured the oil pressure, which was at cold engine around 1 bar and at warm engine around 0.4bar. So I've changed the oil pump which was worn out. After that, i got at cold engine a pressure of 2.5 bar but again when engine was warm, only something around 0.4bar. The ticking sound was gone but there is still the knocking sound from the intake.

The knocking sound is with cold engine not noticable but getting louder when engine gets warm. At higher engine speed, the sound was not noticable.

I've decided to give the engine to someone with more experience ;-) He was verifying all the steps I've made with my mechanic, check the timings, check oil pressure, check compression (3 cylinders are missing 35%) etc. to get an overview - there was no obvious failure. Because of the ambiguous situation, I've agreed to repeat all the steps we have done.

The head was removed again, all parts inspected again, applied a new head gasket etc. putting all together without any luck - there is still a knocking sound coming from the intake.

Currently I'm really disappointed. The assumption now is, that the new head with assembled valves and springs has some issue. I think this could be possible, but i would like to ask if is maybe a different idea for the knocking sound. Has someone an alternative theory?

Thank you in advance.
Best Mario
 
if it is a thud more than a knock it could be inlet valve not seating correctly, disconnect the hose off the inlet, if it is a valve you will hear it thumping and even feel it blow back as the bad cylinder fires. Make sure nothing light lying about when you run it with hose off !
 
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hard to say from that. have you run it with hose taken off at the manifold you will really hear a thumping if it is a valve
Yes, the hose was taken off and the sound gets louder but hard to say which valve is causing the sound. The mechanic said it could be possible that this sounds comes from the short engine....not sure if this is possible...
 
I've fitted a new head, nothing was skimmed. As far as i know the 3 hole head gasket was the thickest. Regarding the lash adjusters, i can understand how a valve will not open but i cannot understand why a valve will not close because of the lash adjusters. Is this possible?
 
I've fitted a new head, nothing was skimmed. As far as i know the 3 hole head gasket was the thickest. Regarding the lash adjusters, i can understand how a valve will not open but i cannot understand why a valve will not close because of the lash adjusters. Is this possible?
how do you know a valve isnt closing , and it cant stay open much else piston would hit it theres very little clearance, lash adjusters can seize so not allowing valve to shut quite fully, or fail so valve barely opens,take cover off and turn engine over by hand checking
 
I didn't know, the assumption is that this knocking sound is because of not closing valve, we have to check. Question is, if there are other options which are creating this knocking sound from intake....
 
I didn't know, the assumption is that this knocking sound is because of not closing valve, we have to check. Question is, if there are other options which are creating this knocking sound from intake....
is compression down on 3 cylinders or just down on number 3
things that hold a valve open or not let it open are lash adjusters, valve could be bent due to piston contact,similar symptoms with a burnt out valve similar with a blowing between 2 head gasket
 
On 3 cylinders is compression down, don't know the numbers exactly....
i am no expert on the td5 engines but i have experienced loss of compression before .... infact i have experienced my td5 starting motor whizzing over the engine 3 times faster than normal as if the starter motor had no load before it burst into life a few hours later


swap #3 lifter to another cylinder location does #3 still low on compression ?

the reason you dont know the numbers was this may of been a relative compression check ?
 
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