1HZ bottom end knock on cold start (1 Viewer)

[rchalmers3]

Vehicle is a 2 year old 78 series truck. Kilometers are very low for its age. Knock is serious in my oponion. Soon as oil pressure starts to build the knock subsides. Warm starts make no noise.

I believe there is something starving the oil feed, as if the supply system (pickup, pump, and especially the filter) is draining back into the crankcase.

I could use some ideas. I will install a known good gauge to confirm it's pressure related. I have thought of arbitrarily changing the filter (he uses OEM, but that dos'nt mean it's Ok) to eliminate a maintenance induced problem.

What are your thoughts?

Rick

 

[roscoFJ73]

Is the knock regular? Both of mine make a quiet irregular knock for a few seconds,I think its a fuel knock rather than something in the crank/conrod

What viscosity oil are they using?

 

[roscoFJ73]

This might be better off in the diesel forum

 

[rchalmers3]

Sounds too deep for me to consider fuel knock, but I won't rule that out.
I'll get a gauge on it and confirm a relation with oil pressure. Seems to be the place to start.

Question, is there a way to change fuel formulation or some other method to rule out fuel knock? Seeing this problem presented suddenly, I am willing to consider a load of bad fuel, even if it sounds like bottom end noise.

Edit: 20/50 is the answer to the question of oil viscosity.

Rick

 

[roscoFJ73]

Sounds too deep for me to consider fuel knock, but I won't rule that out.
I'll get a gauge on it and confirm a relation with oil pressure. Seems to be the place to start.

Question, is there a way to change fuel formulation or some other method to rule out fuel knock? Seeing this problem presented suddenly, I am willing to consider a load of bad fuel, even if it sounds like bottom end noise.

Edit: 20/50 is the answer to the question of oil viscosity.

Rick

I was thinking a bad injector rather than bad fuel,one that doesnt open properly when cold

 

[Clint79]

i read on another aus forum that a vdj79 had a cold knock and it was due to the injecctor timin was out but thats fixed by a computer can a mechanical diesel have timmin out bad or something?

 

[roscoFJ73]

i read on another aus forum that a vdj79 had a cold knock and it was due to the injecctor timin was out but thats fixed by a computer can a mechanical diesel have timmin out bad or something?

I think they shim them or tighten them down or replace the spring,but they have a fixed setting. Last time I had my injectors done it was mainly the springs had gone soft.
This can allow the injector to open prematurely.

The injectors on the D4D systems have their openings controled by puter.
I have heard quite a few stories of V8 and 1KD injectors having episodes of bad knock when cold.
So far only the dealer has the software to fix it

 

[rchalmers3]

Thread revival

Update: The source of the knock on start up was an OEM oil filter with a defective anti siphon valve.

After speaking with the owner, and his recollection the problem started after he changed the oil and filter, I recommended to him that another filter change might by an easy remedy for the apparent oil starvation on cold start ups.

He told me that when he changed the filter, that there was practically no oil present in the used filter. It was damp but drained. He prefilled the replacement filter (OEM) before installation as always and has had no more dry starts. This has been about a week now.

I advised him to pull off the filter in a few days to confirm it is not draining off. I figure since it appears the previous filter was draining off, leaving the motor without oil for about 5-7 seconds each cold start up, and since the symptoms have abated, the new filter should be full if removed.

To learn if I was thinking right, I cut apart the old filter and confirmed that there is indeed an anti siphon valve. Due to my initial unfamiliarity with the filter construction, I cannot prove the exact point of failure, as I had to stare at the disassembled thing for a while and learn the function of the individual parts. After applying understanding, I am able to conclude the valve was either not installed with proper clearances, or the anti siphon valve was installed in an inverted position. I was able to rule out debris with a casual inspection for junk.

I think it is important to note from this experience that even Toyota oil filters are not all made perfect, and some can potentially ruin your very expensive engine. From this experience I have the following recommendations:
1) Buy good quality oil filters (the OEM filter is an amazing dual stage filtration device with anti siphon and over pressure safe guards!)
2) Prefill your new filter before installation.
3) Pay attention "time to oil light out" on start ups after an oil change. Or any time for that matter!

Best wishes,

Rick