Rattling noise on acceleration 1HD FT 80 series

[Dannyb]

Hi All,

I recently purchased an 1997 land cruiser 80 series GXL (HDJ80). She runs really well but I noticed on one of my last trips that there is a rattling noise on acceleration. It disappears when you take the foot of the accelerator and is louder the harder you accelerate.

When I tried searching on the internet all I can find relates to gas vehicles talking about knock. That should not be possible on a diesel right?

So I checked the timing belt and noticed that it is not very tight. I also checked the timing belt on my HZJ75 and there seems to be heaps more tension on that one. That one is spring tensioned though instead of hydraulic tensioned.

Could this cause the rattling noise (i.e. hydraulic tensioner is stuffed) and timing of the valves might be a little bit out. Timing of the fuel injection should still be right in relation to the cylinders though as the pump is gear driven.....

Otherwise, what else could cause the noise. I know this 24 valve engine has bridges etc but I believe that normally valve clearances only get tighter so should not cause noises.....

 

[CycloSteve]

Sounds like it is time for a new T-belt and tensioner. I would not even start the rig until it is sorted. A mis-timed valve train = a very expensive repair.

 

[mudgudgeon]

I agree with above. T belt should not feel loose at all.
If you have any doubts about it, or don't know when it was changed last, its cheap insurance to change it.

Incorrect injection timing can cause noisy combustion. Can't say I know what that sounds like though

 

[Dannyb]

Injection timing shouldn't be incorrect though as the fuel pump is gear driven, so in relation to the cylinders they injection should be right, only the valves might be a bit early or late.....Hopefully I wasn't hearing slight interference between the valves and cylinders....

 

[mudgudgeon]

Injection timing shouldn't be incorrect though as the fuel pump is gear driven, so in relation to the cylinders they injection should be right, only the valves might be a bit early or late.....Hopefully I wasn't hearing slight interference between the valves and cylinders....

I'm not suggesting injection timing is wrong because of a loose timing belt, I'm suggesting it may be another separate thing to investigate that could cause noise. Yes, the pump is gear driven, so timing is (relatively) fixed, but it can be advanced or retarded. Too much advance creates noisy ignition/combustion.

I'd have timing belt at top of the list.

 

[tweeek]

Something to note about your timing belt, it may feel loose until you rotate the crank clockwise slightly. The tensioner will take out the slack. Even a brandnew tbelt and tensioner may feel this way (I just went through this when I thought my tbelt was loose as well despite having only 20k on it)

Put a 32mm nut on the crank bolt and turn. I bet the slack is gone. Unless you are off by a tooth, like the belt is loose enough to skip, I am skeptical if that is your issue.

However, if you dont know when it was replaced last, replacing is good idea anyway as its cheap and easy to do.

 

[tweeek]

Fyi,

Here is the thread I posted when I found my belt loose. General consensus was some slack normal until engine advances.

1HDT Timing belt tensioner