Timing belt tensioner problem

[blakkat]

So yesterday I was making a pull and when I pulled into my garage I noticed it was running weird. I checked the timing belt and the tension is really high on it. I thought it jumped timing but I checked compression and it's fine, also the timing marks seem to line up fine. However after sitting for a while belt tension was normal, but after the compression test it was too tight again. Our tensioners are hydraulic if I am correct? Would a tensioner failure result in a symptom like this?

 

[bryanwheat]

The tension will normally be tighter after turning the engine off. The tensioner will settle down a bit after it has been sitting for a while. If you timing marks are lined up than there is nothing wrong in the timing side. IF you are worried about the tension being incorrect than you can pull the timing cover and check to make sure that it is adjusted properly. Having the tension a little too tight, or a little too loose won't make the car run bad at all. All that matters is that the timing marks are lined up. Check for codes, check for boost leaks, and check for pre turbo air leaks.

 

[Ghost_92TSi]

Tight is good, Loose is when you need to worry about, It'll be a little "softer" after it sits, I believe its the intake cam that rest a little back?

 

[blakkat]

It's extremely tight though, it has me worried it might snap if I drive it.

 

[DirtyJerzeyDsm1]

Most belts also shrink when heated up. So after running the car for a little you may feel really tight but it will be fine. When you say it's running different what do you mean?

 

[bryanwheat]

It's extremely tight though, it has me worried it might snap if I drive it.

As i said, if you are worried about it than pull the lower cover and check it out. It sounds normal to me though.

 

[blakkat]

I mean after I hit 7,000 rpms the car started hesitating severely and sounded like it was backfiring. There was a smell of burnt rubber under the hood coming from the timing belt. Before after shut down the belt would be tensioned with a little movement but relatively tight. Now any time the motor turns over it has no ability to deflect until it sits for a while.

 

[DirtyJerzeyDsm1]

To be safe i would take the covers off. When you d that check the covers see if anything is rubbing. Check the idler. Just check it all. When was the last time the car got a new tensioner, belt, and idlers?

 

[russell3123]

It might not be youre timing belt , it could be one of the drive belts. The back fire and hesitation could be from a bad tune. Is it backfiring through the exhaust or intake? But i would check out the timing belt first.. Pull the plugs and turn it by hand and check the belt for marks or broken teeth .

 

[blakkat]

I'm definitely gonna do that. Also I'm not sure, the previous owner said it was changed recently but I'm not sure. Also it was a popping/backfiring from the exhaust. Drive belts are fine, also already compression tested, and rotated timing belt, both cam timing marks are still in proper alignment

 

[dsmdan83]

I would certainly pull the cover and check it out. Check the balance shaft belt too. It can break and rub the timing belt and cause the rubber smell, not to mention get caught in the timing belt causing the timing belt to snap. I have personally seen this happen and cause the balance shaft to bend and blow-out the side of block.

 

[blakkat]

Alright ill check all those things. I appreciate the help

 

[russell3123]

If its backfiring through the exhaust its running rich so u might have a tunning issue.

 

[blakkat]

I know, but it only did that after the run to 7k and the short time after before I parked it. All other pulls the car felt solid.

 

[pauleyman]

and rotated timing belt, both cam timing marks are still in proper alignment

This doesn't tell you anything. Cam gears must align REALATIVE to the crank. I am not saying this is what happened....but what if the crank slips one tooth. The cams will still line up if you turn the crank over until they are both aligned...but the crank is off. Everything relies on the crank first.
Now, that being said the tension between the cams also tells you nothing. The position of the lobes can affect what's going on there greatly. When the car is running this doesn't happen as the crank is pulling the belt through and there is no room for slack on the trailing part of the belt (firewall side). This is the same reason we turn the motor over to align the crank mark (sometimes it takes full six times) so we can then check the cams. What does this do? It ensures there is no slack on the side on the firewall as all of the tensioning action happens on the front side with the eccentric pulley and the hydraulic tensioner. No matter what it's doing there is one common thing that has to be right. Once you have the motor rotated and all marks ARE right then the protrusion of the hydraulic tensioner must be within the spec in the manual. There is no subjectivity in this measurement. Very simple. You MUST have rotated the motor in a clockwise direction at least a little bit so there is no slack in the back side. You also do this when actually setting tension. It's also the reason (besides the possibility of timing jump) you do not turn the motor ccw as you introduce slack on the side of the belt that can't be tensioned which will throw off any attempt at setting tension. It's very very straightforward and also very very over analyzed over the years. I never understood why.

 

[blakkat]

I understand what you are getting at. Ill have to double check the crank timing marks when I pull the cover. Is there any in way I can tell by the harmonic balancer?

 

[pauleyman]

Sort of. If you set the balancer mark at zero its supposed to line up the crank mark also but I've never trusted it as I've seen too many balancers that have slipped, boogered up timing covers etc. If you use this method I don't think it's a substitute for the actual crank mark. If the car runs well, idles well and generally drives well except for when you're getting on it and then only over 7k, then I doubt it's the timing belt.

 

[fourgsixthree33]

Take a video of you pulling on the timing belt between the two cam gears.

Remove your lower timing belt cover, line up your crank timing mark.

Take a picture of the crank timing mark and oil pump sprocket timing mark.

Take a picture of the cam gears while the crank timing mark is lined up.

Take a picture of the tensioner PULLEY.

Remember to make sure piston 1 is TDC. If it is not, your marks will not line up with eachother. For example, your oil pump sprocket will not be lined up when your crank is lined up. It takes 6 revolutions for the oil sprocket per 1 complete rotation of the cam gears.

The crank turns two revolutions per cam gear rotation.

Post pics and a video and report back.

 

[blakkat]

Alright I will do all of those things this Saturday and post the pictures and video you asked for.