5mm bolt for chain guide pin removal?
 

Howdy friends... I need to prep for my head removal (92 300D, OM602). Can anyone confirm the size bolt I'll need to use the "nut and washers" technique to try easing the chain guide pin(s) out? And can I just remove the upper pin if I am leaving the chain/cam sprocket in place while the head is off? I thought I read somewhere that this is possible.

I am emboldened do get this done after finding that my chain is NOT stretched beyond spec. Depending on how I look at the timing marks and the lines up at the cam sprocket, I am AT WORST at 3 degrees, probably less. The chain looks good, as does the sprocket; chain appears to have been replaced at some point as it is stamped "Made in Japan." Odd, but hey, I'm not complaining.

Thanks!

I think it's a 6mm there.

There's considerable risk to leaving the chain guide in place while lifting or installing the head so that's reason enough for me to remove it. I don't know if it actually has to come out.

The upper pin is the difficult one. The lower pin doesn't put up much of a fight for some reason.

Sixto
87 300D

Thanks, Gents. So 6mm hex head is what I need to look for?

Timing Chain
 

I am not happy to inform you of this information.

This is the Manufacturer of the OE Timing Chain (Drive) System.
Each and every link of the chain will be stamped IWIS.

There is a VAST difference in Build + Assembly quality Between the IWIS
product and ANYTHING else available on the market.

See: http://www.peachparts.com/shopforum/tech-help/23317-have-you-had-timing-chain-break.html?highlight=jwis

I believe that both pins have to come out, and then the chain guide is released allowing you to pull the head without splitting the chain (big advantage IMO). You will need to remove the cam sprocket/gear for this so zip-tie the chain to the gear before you start.

ON the 115 fintail and 123 the bolts that hold the thermostat housing together will work for that purpose. But be sure to use one thats not too eaten away! Bolt, washers and maybe a nut here and there. Don't let the bolt bottom out in the hole though, its tough to get out if you do.;)

Chain Guide Pin internal thread dimensions!
 

No! "So 6mm hex head is what I need to look for?" No!

The pins that support the OM60X chain guides have an internal thread dimension of M6X1. That means that the threaded portion of any bolt or rod used to pull it needs to be 6 MM OD and have the thread pitch of 1 MM (one millimeter distance thread to thread). The head dimension of the M6x1 bolt is usually a 10 MM hex. The 60X engines also use a M6X1 Allen Head bolt to attach the intake manifold.

With regard to these pins, the correct puller is the best way to remove them, but if you are going to use a makeshift method use the best quality bolts and nuts you can get (OEM bolts are usually quite good quality). It is most important to make sure the pin's internal threading is good, running a tap through first with some cutting fluid is advised particularly for rust belt cars. Then you can make sure you get your pulling bolt is threaded in as far as possible to prevent the internal threads from stripping out! It is advisible to use a couple of greased washers between the nut and the socket you use as a standoff. Make sure the socket is tall enough and of sufficiant internal diameter to prevent the pin bottoming out inside the socket before it is completely free. There was a recent poster who broke off the pulling bolt when he kept turning the nut with the pin jammed, broke off the bolt and then broke off a tap repair which eventually required cutting a hole in the backside of the head to eventually remove the pin.

Another caution is make sure that the socket/washer/nut set up allows the bolt to pull straight on the pin, if there is much of any angle when the bolt it drawn it will be pulled sideways and could cause it to break off. Good Luck!

a quick search brought up these threads regarding guide pin difficulties:

http://www.peachparts.com/shopforum/diesel-discussion/240053-broken-draw-bolt-timing-chain-guide-pin.html?highlight=Chain+guide+pin

http://www.peachparts.com/shopforum/diesel-discussion/137770-broke-bolt-off-timing-rail-guide.html?highlight=Chain+guide+pin

http://www.peachparts.com/shopforum/diesel-discussion/122682-need-help-603-head.html
&highlight=pin+threads+stripped

the addition single posts in other threads that describe guide pin difficulties are too numerous to list. Some times things go easy sometimes they don't, hope for the best but prepare for the worst.

Cautious vs. careful; only your hair dresser knows for sure. :rolleyes:

Its good to be cautious but really just be careful. This job is pretty easy and if you just take your time it will work just fine.

When I was pulling the guide pins on the m117 engine, I found that chucking a m6x1 bolt in a slide hammer made quick work of them, even with the years of crud trying to glue them in.

Rental body work slide hammer from Shucks ($6/day), two pack of 6x1 bolts ($1.20?).


That being said, it doesn't work if you don't have clearance for the slide hammer in front of the engine!

Really unless you have a special tool to do otherwise a bolt from the thermostat cannot be beaten. By the time you get half the collecting done for any other option with the little bolt you will have it done.

Thanks for the tips! I have read many of the guide pin removal threads, and just wanted to be sure I had a handle on this before starting. I had hoped to have the head out to take it with me to Guard duty this weekend, as the NDI shop has offered to inspect it for cracks for me for free... but I'll just take my time and get this done CAREFULLY rather than hurry the process. It's -13 degrees with wind chill this morning. I doubt it's going to warm up much until the weekend, so it may just have to wait.

Thanks again!