timimg chain side rails in crankcase

[emmydotnet]

I will be replacing the head gasket and also replacing the timing chain and rails. The car is a 91 560sel with about 197,000 miles on it. my question is, do I need to replace the side rails in the crankcase as well? I think there are (2) rails down there. If so, any tips would be appreciated.

thx

[hey_allen]

From all the comments I've heard, the lower 2 rails do not fail traumatically, and require removing both heads to get the front timing cover off.

If you're already pulling everything else off the front of the engine, and both heads, you might as well change the lower guide rails.
On the other hand, if you only have the one head coming off, and are not already removing everything else on teh front end, I'd leave them be.

I just got done refreshing a 500SEC engine, out of the car, and didn't replace them, if that's any help in the decision.

[porkface]

i've heard of 1 failure after a typical chain, rail and tensioner replacement. that car was close to 300k in mileage. i have done the lower rails with the cover off because it's cheap insurance. i would not hesitate to ignore yours, if the mileage is correct. broken odometers will fool you on total mileage. good luck, chuck.

[emmydotnet]

thank you for your responses. I am inclined not to replace the bottom rails for the same reason as most that I have read - mileage is below 200K. I started working on the car today. The intake is ready to come-off. Except for that one allen at the back of the left head holding the EGR pipe, everything has been taken off. I plan to complete taking off the heads tomorrow. I do not know of a local head-shop ( San Jose), so I will probably send if off to Metric in LA.

[hey_allen]

With both heads already going to be off, I'd consider it more than in my own case, but it would add all the complication of having to remove the oil pans and that "fun".

As far as the sticking allen screws go, if you start to strip one, I can't recommend the "impact screwdriver" tool enough. It's a handle with a 3/8" or 1/2" socket drive on the nose, and a hammer stiking surface on the rear. You put on the bit appropriate to the job, or a socket in this case, turn it the proper direction as if you were going to unscrew the fastener, and whack it with a large hammer. It helps to jolt them loose, rather than just stripping the head out (as I managed to do to a couple that were seized, on my engine project. Oops!)

Another fine wrenching friend is a good penetrating oil, as you most likely are well aware!

[emmydotnet]

I managed to strip one socket screw head and now it is rounded. It happened when I was trying to remove the screw. any tips and suggestions?

thx

[Rob Pruijt]

If you can access the head from the top/side you can try to loosen it with a chisel. Take a heavy hammer and a sharp chisel, make a sharp dent in the top/side of the head, put the chisel in the dent pointing counter clockwise and hit it hard with the hammer. Be very carefull not to hit your hand or an expensive part of your car!!

If the bold is fixed with locktite or a similar product heating it will break the bonding.

[emmydotnet]

I got the stripped allen out using 'Sears Bolt Out'. works great.

I got both heads out and ready to send the heads to metric for reconditioning. I was able to get the the head bolts at the back of the heads by jacking up the engine ( about an inch) from the oil pan, one side at a time. I am not sure this will work during re-assembly as I do not think there is enough room for a torque wrench, even by jacking up the engine. any suggestions would be appreciated. I guess this may be the reason why there are a lot of head leaks at the back of the head because the bolts at the back may not be properly torqued.

thx,,