Stretched timing belt 1HZ (1 Viewer)

Joined
Mar 25, 2021
Messages
33
Location
Melbourne, Australia
I replaced the belt in my 80 about a year ago, was time. After that job, we went away up country for a weekend. I noticed a new noise at highway speed.
We get away not very often in the past and the truck does few miles around the city as i mostly work from home. So its mostly driven under highway speed.

So wo decided to drive from melbourne to QLD just after christmas, and spend new years with our daughter at the Gold Coast.
I got to and started prepping the old girl for travels. Doing all the small jobs id been meaning to.
After they were all done i had another look at the timing belt.
What happens at highway speed, is between power on and coasting, theres a kinda vibration noise, sounds like rubber not metallic. That spot on the highway when youre diff makes a little noise, and disappears powering on or lifting foot off. Reminded me of my youth and stretched timing chains. I knew it was the belt.

I had used a Gates belt and new genuine tensioner and idler. So doubting the Gates belt, i bought a new genuine belt and tensioner spring. Taking the old belt off, i placed it beside the new one and the new one almost i]fit inside it, it was that much longer. I counted teeth 3 times and they were the same. After i fitted the new belt and went for a run, the increase in power was startling, so it had clearly been running with not enough timing. I didnt hear the noise directly, so thought alls good!
But then got out on the highway and there it was, way way less but still apparent.

Ive done 8000k's since and its loosened up a little more, noise seems to be returning slowly.

So im trying to figure out what could be causing this. Given the belt is driven by the injector pump, the load on the belt is the camshaft and workings. Id think any kinda seizing of a bearing would be apparent noise wise and not run for long before doing something nasty.

I didnt replace the idler tho this time, but it does appear to move as required without hindrance.

Has anybody heard of this occurring with a HZ or HDT?
Any Melbourne folk have a good mechanic they can refer? Last one i used cocked up a simple rocker gasket after doing the shims..
 
Joined
Jul 22, 2003
Messages
18,367
Location
Perth Western Australia
Gates' belts are top quality, I've never heard of anyone getting a bad one and they are sold widely in Australia.
Maybe your harmonic balancer is on its last legs. Have a look for cracks in the rubber.
Or a universal joint is on is way out. They have that off on vibration depending on your foot
 
Joined
Mar 25, 2021
Messages
33
Location
Melbourne, Australia
Yeah it’s actually the belt. I took the cover off and just revving the engine you can see that it flaps around on the off rev.
I can’t see any reason the original idler I bought with the Gates kit last year would be the culprit but I think I’ll order a genuine idler and replace it. Perhaps there’s something going on with it’s relationship.
 
Joined
Jul 22, 2003
Messages
18,367
Location
Perth Western Australia
Did you you use the old spring? You can buy just the spring from Toyota, its only $12 from memory, no need to buy the complete idler. There is specs for idler spring tension in the FSM
 

Users who are viewing this thread

Top Bottom