Can someone please post a picture of a stock 2.8 timing chain tensioner?

For anyone that has been following my troubles lately my 87 GT died a few weeks ago. I came to the conclusion the timing chain had jumped. Today when I tore it all down it appears that three of the four ears of the stock timing chain tensioner have broken off. I need the pic to verify the tensioner is infact the problem.

Tomorrow I will drop the pan to see the what the what metal is in the bottom end.

Hank

The V6 does not use a tensioner. What you're thinking of is the chain guide. Its main job is to minimize resonances in the chain at various RPMs. Here's a pic of mine:

As you can see, one corner was broken on mine. I just smoothed it over and removed any loose material before reinstalling it with a new timing chain and gear set.

JazzMan

JazzMan,

Which corner was broken on yours? I see the two corners are okay on the bottom. Should there be simliar corners at the top of the guide? From the looks of it at least one of the corners broke off my guide and I now assume they are floating around in the pan. What do you think the chances of saving the engine once the broken corner gets into the pan?

[This message has been edited by Hank is Here (edited 11-28-2003).]

Hank,
did you check if the timing marks still line up correctly? Having seen the photo from Jazzman, I am now 100% convinced that the jumping chain is impossible, and would love to see a photo of your timing chain in situ as it is now.Is that possible?
fierofetish

fierofetish,

I'll grab a pic of my timing chain later tonight. The timing on my engine is right on, it did not jump. I do think that a chain could still jump. In my case I am glad I pulled off the cover but sad to see what I found.

The corner that is broken is the upper right one.

The all-metal gears and chain used in the Fiero 2.8 can't jump, there's no room in the timing cover. That is, assuming that it isn't worn so badly that the teeth are mostly gone, but if that's the case you'll have much bigger problems to worry about than the timing chain.

The casing of the chain guide is hard rubber or plastic. Any bits that break off should get caught in the pump screen, and smaller pieces would get pulverized by the oil pump. I'd pull the pan and clean it out well, put a new guide on along with the chain and gears, and not worry about it too much.

JazzMan

Attached is a pic of my timing chain setup. It isn't as clear as JazzMan' but hopefully you can see the broken corners in the upper right and lower right. Should the upper left corner look like the other corners as well? If so I might have broken 3 of the 4 corners

quote Originally posted by JazzMan: The all-metal gears and chain used in the Fiero 2.8 can't jump, there's no room in the timing cover. That is, assuming that it isn't worn so badly that the teeth are mostly gone, but if that's the case you'll have much bigger problems to worry about than the timing chain. JazzMan

Sorry Jazz, I really don't want to disagree with you, but I thought the same thing. I had a customers 86 SE 2.8L in the shop this summer, and it did infact jump the timing chain a tooth. This was in an engine that had all the teeth on the cam sprocket and the crank gear.

I myself thought it impossible, and was surprised to find it.

Now I don't want to start another tread bashing like the last one the other week, I'm just stating that although it is very highly unlikely, it can happen.

peace dude

[This message has been edited by jelly2m8 (edited 11-29-2003).]

Hi jelly2m8! I wonder if you measured the old chain against the new one? It would have to have stretched by 1.5 inches longer to jump a cog.If you look at the photo from Jazzman's thread,and imagine the engine running, the chain between the camshaft wheel and the crankshaft wheel on the right will always be tight, because the crank pulley is pulling the camshaft wheel constantly.Surely with this being the case,the chain cannot jump a cog on the crankshaft wheel.Therefore the jumping must take place on the other side, where the chain between the crank and cam wheels would always be slack.Now the chain cannot jump just one tooth, because the tooth would have to engage the next link but one, meaning that the chain would pass over the cam wheel like an inchworm with his back up!!No way. Like I said, it is impossible for a chain to stretch that much without breaking,and if it were,just for the sake of it, why wouldn't it jump again and again?If the chain was only one cog out, by the way, it would still run, but not very well.I think that these cases are caused my Man alone,not jumping chains.By the way, how far out was the timing, if you can remember, and was it advanced or retarded?fierofetish

quote Originally posted by fierofetish: Hi jelly2m8! I wonder if you measured the old chain against the new one? It would have to have stretched by 1.5 inches longer to jump a cog.If you look at the photo from Jazzman's thread,and imagine the engine running, the chain between the camshaft wheel and the crankshaft wheel on the right will always be tight, because the crank pulley is pulling the camshaft wheel constantly.Surely with this being the case,the chain cannot jump a cog on the crankshaft wheel.Therefore the jumping must take place on the other side, where the chain between the crank and cam wheels would always be slack.Now the chain cannot jump just one tooth, because the tooth would have to engage the next link but one, meaning that the chain would pass over the cam wheel like an inchworm with his back up!!No way. Like I said, it is impossible for a chain to stretch that much without breaking,and if it were,just for the sake of it, why wouldn't it jump again and again?If the chain was only one cog out, by the way, it would still run, but not very well.I think that these cases are caused my Man alone,not jumping chains.By the way, how far out was the timing, if you can remember, and was it advanced or retarded?fierofetish

It was jumped plain and simple, I'll venture as far to say that I've worked at more of these 2.8's than most people on this forum combined.

Like I stated several times already, I thought it impossible, I checked and double checked, yes it was jumped.

If you don't want to believe me fine, just don't go telling people it is physically impossible.

Thats it I'm done, I have no need to defend myself. I have never lied on this forum, and have no intentions of doing so now.

I apologise sincerely if you think I am calling you a liar:far from it, but you must equally not tell people on this Forum that it is possible when there is no proof!!Nobody can physically see the chain jump, and because there seems to be no other option to you,doesn't mean that it is so.All I ask is a feasible explanation of how it can jump one or more teeth, and only once and then no more.The perfect example of how a chain can jump a cog is on a bicycle derailleur gear change, which has a springloaded arm which allows the chain to "stretch" to move from one gear to another. In this case it is possible for the cog to slip if the teeth fail to engage straight away, resulting in the Riders reproductory organs coming into contact with the crossbar!!
As Jazzman pointed out, there is just not enough room for it to happen in the V6.The only difference between this system and that used by many British cars is that the uk built cars use an actual spring-loaded chain tensioner, which,if broken and thus ineffective, allows the chain to flex enough to miss a cog.Inevitably when this happens, it misses quite a few, in fact,and ends up with serious damage to the engine.
I appreciate we have very differing views on this subject,and I would point out that I have been working on cars with chain-driven timing for 40 years,and so probably in the region of 300 cars with timing problems, and never come across the situation mentioned, except in modern cars using the flexible synthetic timing belt,on which it happens very frequently unless the belt is changed at very regular periods.

All I can say is that Jazzman and jelly2m8 has the green rating bars.
Don

That is very true, and yet the strange thing is, they have diametrically opposing views on this subject!!I am the first to back down and apologise if I am proved wrong,as you can see in the thread by buddycraigg recently in GFC about speaker connections:I was given a logical argument proving me wrong.I confirmed that argument by consulting www.howstuffworks.com which confirmed their opinion, and immediately backed down.It takes anybody to make a mistake, but an honest one to admit He was wrong !!!as I was in that case.Egg all over my face, in fact.