Timing...

'lo guys...it's me again. You might (not) remember me from this: http://www.automotiveforums.com/vbulletin/showthread.php?t=731085
With my old 2.5 Duke and its timing gear problem.

Well, I've finally got the money to get the gears fixed...but another problem has arisen.

I explained to the mechanic I'm having do it what the problem was, what the symptoms were, and how you guys said to fix it. He says that he's worked on a few of these engines, and has never heard about drilling out the oil galley plug, and would be hard-pressed to do so out of concern for the oil pressure to the rest of the engine. Is there anywhere, any article on the web that details the procedure? I might be able to convince him to drill it out if I have something to show him.

Also, the metallic knocking has stopped coming from the cover, in its place is an oil leak. I'd originally assumed that the knocking was one of the gears wobbling on its shaft, and had eventually worn a hole in the cover. I told him this as well, and he says that it sounds more like something a chain would do, and that how the gears are made it's simply not possible for them to wobble the way I think they were.

I've read a couple places online that say GM started using timing chains in these engines around 1990, which happens to be my car's year. My question is, do any of you know a way to tell, beyond a doubt, whether it's a chain or a gear system, without cracking open that cover? I have the gears already, but they're useless to me if it's not a gear drive after all. I need to know which though *before* he opens it up, since the chain is a special order item...

Thanks for all your help, guys. I know I'm being annoying :uhoh:

I too disagree will drilling the oil holes as it could allow the top of the motor to not get oiled properly-ie lack of oil because it drains to fast.

And that's a NO on the knowing what you have inside.
Same with knowing whats making that noise.... investigation is the only true way to know.

As you already know this was the year they changed the timing sets, but yours could be either way.
I've seen them all with chains if that helps any.
But that does not mean your has a chain.

Here are a couple links I scraped up :D
This one (http://www.autozone.com/az/cds/en_us/0900823d/80/0e/f9/14/0900823d800ef914/repairInfoPages.htm)says you dont have a chian, but its for the cutlass 2.5, same iron duke though.

This ones for grand ams (http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/09/78/1a/0900823d8009781a.jsp&eraseCrumbs=YES), search the links on the right.

Hope that helps!

Advanced auto only lists a timing chain for that year. I have not seen a gm car with a timing belt since the mid 80's.

Gee, both of those links lead to directions and pictures that look suspiciously like the ones in my Hayes manual :p

You guys don't have to read what I'm about to type out, it's just here for future reference, in case someone runs into this problem :D

I'm about 80% sure I have a timing chain. Evidence as follows;

Read somewhere that the knocking sound I heard is referred to as "chain slap", caused by a stretched/undamped chain smacking against the timing cover, which also wears a hole causing an oil leak much like the one I have now. Hmm.

Since my existing cover obviously has a hole in it (at this point, if I want to drain the oil, all I need to do is run the engine :shakehead ), I bought a new cover and...what do you know, it looks just like the cover in the Hayes pictures. The gear drive cover looks quite different, more blocky and ridged, while the chain cover is smoother and frankly, prettier.

My problem got worse over time. Chain stretching out? Damper slowly failing? Hmm. Everything I've read about the gears says that they fail immediately and spew fiber bits into the oil pan---I've seen no fiberous stuff, just decreasing performance, what feels like missing when the TCC is on (engine under a load), metallic knocking and crappy MPGs.

I'm guessing what feels like missing actually is, of a sort...the valves opening and closing at improper times due to the mechanical timing being so far off.

The conclusion? 'tis a chain drive, which despite my having dumped $140 on a set of gears I can't use (hope I can return'em!) makes me very happy...don't have to lift the engine up and out to replace the chain and damper, hoorah. $150 saved (can do it myself, woo, doesn't count as hard labor, which I'm supposed to avoid).


Thanks a lot for all the help, this forum and its members have been invaluable :grinyes:


On a final note...
Advanced auto only lists a timing chain for that year.
Every site I've been to lists my year as having a chain standard. The reason I didn't believe them is because they also list '89 and older as using a timing chain, when I know for a fact that they use gears. Auto part stores are great and all, but if in doubt, research yourself. It'll keep you from making a mistake like mine :\

Yeah skibum, Inafog kept saying it had a gear drive, maybe later on in 1990-91 models.

I've seen many 2.5 iron dukes, but none had a gear set up.

Mr. Guy if the timing was to far off you would know.
Either due to poor running conditions or the noise of the valves hitting the pistons.

Also you should be able to return the gears set , hoping you saved the receipt .....

ps - wouldnt hurt to clean up any gunk inside your timing cover area(and passage ways), then after you're finished change the oil. :thumbsup:
Junk can fall in the oil pan and could possibly clog the oil pick up. ;)