EGR Defeat

OK guy’s need you help and advise once again. Freed my EGR from the open position to closed by penetrating oil and a few knocks. Now I think it maybe stuck in the closed position. Took the time to replace the new unit taking off the lateral throttle linkage to finally get to the EGR, which was not an easy task. Got everything back together and had a massive vacuum leak.

Ready to give the EGR a boot and plug the line. Is there a part that will effectively plug the line at the female ends? The nut is 24mm and the tube is .5” in diameter. Went to a local hardware store and found a .5” nipple to screw onto the male end, and then thinking placing a cap on the nipple. Unfortunately, the threads were different to make this work. Any suggestions?

As usual, I surely appreciate your help and advise.

[ctaylor738]

I plugged the manifold hole. Mercedes has the plug. I remember it being the same size as the ones on the outside of the intake manifold.

Thanks for the reply Chuck. Went back to your previous post concerning plugging the EGR. You mentioned it could be found on 14/1, #16 or #18 in the parts catalog. Do your recall which one it is? Also, did you cap it off at the intake manifold, or at the pipe that leads into left side of the EGR? Am thinking to plug mine at the left hand pipe for two reasons:
1. In case someone wants to fight the darn thing later a piece of it will be in place to guide the way for installation.
2. Won’t have the take the carburetor off to plug it at the intake.

As I have not seen this as yet, I may be all wet. Will it cap the left hand pipe effectively as to prevent a vacuum leak?

Appreciate you time and advise.

[ctaylor738]

Unfortunately, I don't recall which one it was. I do know that Andrew the Parts Guy had to get the M110 PAPER book from under the counter to figure it out. The parts book lists "Screw Plug xx MM" and you want the one where xx is the size of those plugs on the left side of the intake.

But I will look at the book and my receipts tonight and see if I can be a bit more definite.

The problem with plugging the pipe is that you need a metric pipe and metric threaded plug - not a Home Despot item. Besides, with all the practice you've had, you can have that carb off and on in 10 minutes. You need to check the puddling in the intake anyway. :-)

Yeah, doing R/R on the Solex all summer I should be able to field strip it blindfold. As it is now finally running correctly, absent of a EGR leak, don't want to fuss with it.

Going to give the EGR insall another go today. Don't think I was getting the bolts on tight enough to compress inside the unit. Such a tight spot to get a 24mm wrench into as the bolt always hits a "dead spot" where the wrench won't bite onto it. Time to get the Rigid pipe wrench out.

Or,

Just replace the old one, at least I knew that one plugged the line.

[ctaylor738]

Looked at the book.

There are two types of plugs used in the manifold #16 is the larger, and I believe that was the one that fits. They are like $1.50 each, so you might want to buy both #16 and #18 to be sure. Obviously, it's the same diameter as the male fitting on the front part of the tube.

Thanks again and appreciate your help. Placed the EGR back on yesterday. Is holding vacuum when closed @ 10 in Hg with timing advanced to 15 degrees BTDC. Funny thing, when opening the EGR with a Mityvac, the engine stalls. Got a major vacuum leak somewhere.

Will be going looking for leaks today once again. Borrowed an advancing timing light and checked to check timing. When the timing is set on 15 degrees, and advancing the light to get a TDC reading, I'm off by 5 degrees according to the light. Think chain stretch is causing the vacuum problem?

[psfred]

Gympie:

Opening the EGR at idle will always cause the engine to stall -- i't supposed to be closed then. Not a vac leak, no engine is goind to run with that much exhaust in the intake!. It may never open fully, if it does it will be at moderate throttle. Should also close at full throttle.

The distributor also has a mechanical advance -- this is why there is a set speed at which you set the advance with a light. Total advance should be 26 degrees BTDC at about 3000-3500 rpm, although I don't actually suggest you check at that rpm. Basic advance should be set "by the book" to what the speci is -- in your case, 7 degrees before top dead center with both vac lines attached to distributor. The retard line (distributor side of vac can) goes to the front of the carb, advance line goes to the back, beside the vacuum governor and fuel return valve. If you have those reversed, you will have running problems -- happened on our '68 Ford Wagon -- full advance at idle and prgressivly later timing as the throttle opened, exactly the opposite of what was intended. Took forever to find.

Peter

Peter

Thanks Peter for the response and advise once again.

You are correct in the EGR only opening at partial vacuum Found that part in the Service Manual today.

Don't have vac lines going to the distibutor. Have been told that the engine will run better at 15 degree BTDC to compensate for the high elevation in Colorado and Denver.

[ctaylor738]

Peter makes a good point. According to the manual, the EGR valve should not open in P or N and only in "driving positions" when there is "high vacuum."

Thanks Chuck for the reply. As I posted in response to Peter, I understand the function of the unit.

A few questions remain in my mind.
How is chain stretch diagnosed?
And if a chain is stretched enough to alter timiming, would it have a direct result in lower engine vacuum by mistiming of the valves?

Appreciate your input.

[psfred]

Gypmpie:

You should have a dual action vacuum advance on your car, unless you have fuel injection.

The proper correction for high altitude is to put leaner jets in the carb (actually larger air tubes in the Solex, I think). Timing should stay the same, you need to correct for the difference in air density to keep the fuel mixture correct. If you plan to drive at low altidude out here in the flatlands, you will need to put the originals back in or you will run rich -- another argument for fuel injection.....!

To check chain stretch: Remove valve cover. Set engine to TDC on the #1 compression stroke (both intake and exhause valve cam lobes pointing up) by matching the mark in the cam with the mark on the tower. You can use either cam -- exhaust side will be slightly later than intake side. Then read the degrees off the crank pulley.

You must, of course, rotate engine in direction of normal travel using the crank pulley bolt, and stop when the cams are lined up, not the crank indicator. It won't match at TDC, the difference at the crank is what you need to check. Make sure chain tenstioner is tight, too.

Less than 4 degrees is fine, 4-8 you need to plan on a new chain, more than 8 get it outa there soon!.

Valve timing can be set with offset Woodruff keys (the little semicircular thing that keys the cam gear to the cam) -- they are available in 2 degree increments up to 10 or 12 degrees (although I would only use 4 degrees -- more than that, replacing the chains makes more sense).

And yes, incorrect valve timing will cause low vac and running problems -- basically a late cam requires more rpm to deliver the same power. Eventually, wear will make the cams so late you loose power.

Peter

Thanks Peter, again you are a lifesaver.

As to the distributor, unless mine is a fluke or has been changed, it has no vacuum advance on it. Has been a quandary to me as well. The service manual pictures all show the distributor with an advance connected.

Thanks for the tip on checking chain stretch. Was also thinking an advancing timing light would do the same. When setting the timing at 7 degrees BTDC, I should be at zero on the dampner if I advance the light 7 degrees, no? Any diffrence would indicate degree of stretch.

Will give it a go today. Saw another way to do it with a dial indicator in the manual so will give them both a try. Your method is much simpler! Hopefully it will not have to be done, but the engine does have 109K miles on it. After 26 years, may be wise just to change it for the grins involved.

[psfred]

Gympie:

Can't use an advancing timing light to check chain stretch. It will show you mechanical/vacuum advance operation. Since the distributor is adjustable, you cannot determine relative position of the driveshaft to crank (chain stretch) by looking at ignition timing.

I'll check with Hans about the distributor -- someone may have swapped a later model one it when the original wore out -- this will cause all sorts of problems for you since you won't be able to set the timing correctly on it.

Avoid setting the timing fast -- we have a friend who always does to "got more power" -- he has this funny problem with overheating and engine longevity.....!

Peter

Peter, thanks again for the reply.

Houston, we have a problem

Just finished doing a TDC check with cover removed. Not good news at all, in fact I'm puzzled. When the cams are markings are aligned to the referense mark, the dapner marking is off the scale. That is, the dapner pointer is beyond the ATDC mark readings. The nearest reference I can is by the "electronic" sensor thing-a-ma-jig that is to the right of the pointer. That reading would be 5 degrees ATDC. It must be off at least 25 degrees! Looks like I have a job ahead of me.

Asking your thoughts once again. When replacing the chain should the tensioner and guides also need replacing as a matter of general principles? And, was told that a timing chain guide from Assenmacher Specialty Tools cuts this job from a 4 hour job into a 1.5 hour job. Ever used one?


Thanks again.