exhaust valve will not adjust. - Page 2 - PeachParts Mercedes-Benz Forum

blackestate · #16 01-15-2009, 10:21 AM

Thanks for all the help, I can be hard headed at times,
I was trying to adjust the top nut, but it will not go any lower, because the bottom nut will not move down to allow it to adjust further but the two nuts will tighten to eachother. It is my understanding that you adjust the top nut, then jam the lower nut into it. But it seems that if the lower nut is not low eneough on the valve, it has to be lowered, until the adjustment is good, then brought back to the top nut and jammed into place.
I can not even get a .002 gauge into the area, so it is contacting the cam and not adjusting at all.
On the valves that did adjust I had to turn the bottom nut about 1 to 1.25 turns to allow the top nut room to travel down and make the adjustment. That is not possible on this, because of whatever is going on. So Monday, I will start by pulling the rockers for this cyl. and see if I can find a damaged valve stem, or a bad nut. I also should make sure there is a "key" in the valve, and retainer at the top of the spring, if not, the retainer also will need to be replaced.
is there a spring compressor that I need to use?

jt20 · #17 01-15-2009, 11:43 AM

you do not need a spring retainer or a spring compressor for this assembly. (see picture on first page)

Here's a last resort BEFORE you start dismantling:

-Loosen the nuts from each other.

-find an open ended wrench that is large enough to span the hexagonal keeper on top onl.
- without contacting any other part of the valve assembly, use this to apply downward force and relieve the lower nut from pressure due to spring force.
-since you said the nuts will counter each other well enough ,there must be threads and perhaps the assembly is just spinning or there is just one bad thread on the valve shaft. The force from the spring and keeper is restricting the nut from a catching a good thread on the valve shaft.

despite the success of this procedure, you want to consider replacing both nuts. If yuo can get the valve lash to spec., I would not consider removing the head to replace the valve unless there is considerable damage to the threads of the valve shaft.

vstech · #18 01-15-2009, 11:51 AM

I don't want to seem like I think you are an idiot or something, but just to be SURE...
you are putting the cam in a position where the lobe is pointing away from the valve right???
you will NEVER get the adjustment loose enough with the cam pointing down...
ok, that said, you should be able to loosen the lower nut down enough to adjust the upper nut away from the cam... unless you are dealing with a bent valve... in that case, you're gonna have to pull the head. see if you can get a pic of the adjuster posted here for us.

bgkast · #19 01-15-2009, 02:15 PM

Sometimes the lower lock nut binds. Use a screwdriver or something to hold the large flat nut under the spring while you try to lower the lock nut more.

blackestate · #20 01-15-2009, 03:49 PM

I am often an idiot. More than that if you ask others. But this time the lobe was up.
I did not see a large flat nut under the spring. I will look again. I stopped the large one on the top that we are refering to as a retainer.

I will do the compress the spring/ see if I can get it to move thing first. if not then remove the rockers and go from there.
Even if this works, I would still need to remove the rockers to change the nuts,
You guys are at least giving me hope. When this all started I was really bummed out.

Thanks
Doug

blackestate · #21 02-18-2009, 08:05 PM

Ok here are some photos of the valve that would not adjust. Both of the nuts are bad, and also looks like the valve is bad? It is the one on the left in the picture of 2. The other valve is threaded to the end.
So,
How hard is it to replace this valve. I do not know what shape the rest of the engine is in, and it blows a blue smoke. This is a new to me car.

Or do I pull the engine from the 85CA model and place it in this 83? will the trans also need to be changed, or will it not swap?

How long should these take for a 1st time?

thanks
Doug

jt20 · #22 02-18-2009, 08:23 PM

Quote:

Originally Posted by blackestate

Ok here are some photos of the valve that would not adjust. Both of the nuts are bad, and also looks like the valve is bad?

Take a better picture and maybe we can tell.

Quote:

So,
How hard is it to replace this valve.

the head has to come off, replacing the valve is easy, but getting a new one ground and finding a shop that will grind just one valve and one seat will be even harder.

Quote:

Or do I pull the engine from the 85CA model and place it in this 83? will the trans also need to be changed, or will it not swap?

trans will most likely need to go with the Ca engine - it is controlled differently.

and the intemediate plate (starter mounting plate) is also different.

Quote:

How long should these take for a 1st time?

taking off the head alone could take a good day for a cautious first-timer

pulling the engine also takes about a day, little less ... same circumstances, taking your time.

jt20 · #23 02-18-2009, 08:25 PM

I can't really the see the affected area in the photos.

You might consider rethreading the valve shaft if you can tighten the locknut all the way down. You may be able to do this w/o removing the cam. Cleanliness will be your main obstacle.

bgkast · #24 02-18-2009, 08:46 PM

Pictures are kind of hard to see. If the threads on the valve are only slightly damaged you could try to clean them up with a tap and install new nuts. Swapping the engine should take a long weekend. You should be able to use either tranny. I believe the '85 has a different torque converter and transmission, but they should all bolt up the same.

Let me know if you need a hand.