|
|
|
As you can guess from previous posts I have been wreslting with brake issues.
So far I have replaced the junction box, hoses, and a couple of lines...but I still have this weird problem that hopefully has a simple solution. When I bleed the brakes (using power bleeder) i get great pedal, however, when i turn the car on I have no pedal. By peeking under the hood I see that when I press on the pedal fluid bubbles up in the first chamber. I'm not sure if this is normal or not. I re-bled the line and same thing. This is a brand new MC. I pre-bled the MC by running hoses from plugs back into resevoir and pushing with a wood dowel until only fluid was coming out. I am fairly sure (I say fairly cause this is my first MC replacement) that no air was left. Is there any possible way the power booster is screwed up? I had the crazy idea that maybe air was escaping around the push rod and into the MC but it's these ideas that get me in trouble. Could someone please save me from another brake bleeding session or mechanic bill.
|
|
-
|
|
|
Thanks everyone for the help. I didn't give up after all. Instead I drained the whole brake system and blew air through to clean all lines from junction box on. Then I rebuilt all the calipers with new seals, Finally I bench bled the MC again. Gravity bled the system first and then used the pump to finish it off. Wa La, I got my pedal. Did notice that the front right caliper is leaking fluid through the bolt holes. Figures cause it was a rebuild. In the midst of all this drama the check engine light came on. Also it appears the ball joints aren't youthful enough to handle the heavy duty springs and shocks I threw on cause there is a noticeable wobbly noise up front. That's my next mission. Also I have a pesky temp sensor that works intermittently. The drama continues. Thanks for all the ideas ya'll! I appreciate it.
|
|
-
|
|
"Did notice that the front right caliper is leaking fluid through the bolt holes. Figures cause it was a rebuild."
Do you mean a purchased "rebuilt" — or did you actually separated the caliper halves?
If so, did you replace the sealing o-ring/washers?
Is so, what is the part # and where did you get them?
I've never considered caliper splitting as a DIY job, but have replaced pistons and seals with the caliper intact before. Art Benstein opened, inspected, and photographed a Front Caliper in detail, as shown here.
I realize this is after the fact, but thought you would appreciate seeing one of Art's many photo essays. He has a nice shot of the "punch marks" on the bottom of each half. If you ever see one of those marks on the TOP of an outer half, you're looking at mismatched halves.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
|
|
-
|
|
|
I meant rebuild as in bought. I have split calipers before and not replaced the little o-ring much to my dismay. If anyone knows where to get the right size I'd like to know for future reference.
|
|
-
|
|
|
"By peeking under the hood I see that when I press on the pedal fluid bubbles up in the first chamber."
(Sorry about coming in late, didn't notice) If pedal drops to floor, it's probably air in the MC. Since you are seeing air bubble up in the reservoir, assume it is being sucked in on pedal uptake. Most likely at the brake line to MC fitting. Tighten the fittings there.
But first, depress brake pedal, block/hold it down then tighten fittings. Release pedal. Check for firmness. If still not firm, loosen fittings, depress pedal and hold it down, tighten fittings, release pedal, test for firmness.
Basically, you're "bench bleeding" the MC on the car by pushing air-fluid out the ports (brake fluid is cheap enough so no need to recycle it back into the reservoir. Just protect paint) and by closing off the ports before pedal release, fluid from the reservoir replaces that expelled. No need for complete brake bleed.
--
1980 245 Canadian B21A with SU carb and M46 trans in Brampton, Ont.
|
|
-
|
|
|
Hi Again
What you suggested, being loosen the m/cylinder nuts and have a helper is how I found out that was the issue.
I also didn't understand why this would be a issue, But by looking at scematics of a vacuum booster they are only designed to work within a certain amount of travel, If you exceed those parameters the vaccum assistance diminishes.
Now how to adjust the pushrod clearance. It's rather drawn out so bear with me. Although quite simple when you think about it.
(this is qouted verbatim from the manual)
A. Measure the distance between the face of the attaching flange on the master cylinder and the centre of the primary piston. (between the face that attaches to the booster and the hole in the piston where the relay rod pushes the m/cylinder piston)
B. Measure the projection of the thrust rod cap from the sealing surface of the booster. The thrust rod cap should be pressed all the way in and there should be a partial vacuum in the booster. Adjust the cap on the thrust rod inward (in your case outward) so the difference between the 2 dimensions is between .1 and 1.0 mm
Thats how the manual says, A simpler way is to remove the union nuts on the master cylinder (bleed once again). Have a helper to get a idea of how much play there is between thrust rod cap and piston seating surface. And remove m/cylinder and wind adjustable cap outward as required.
Now I think this will be all you need. Let me know how you go????
Thanks Greg
|
|
-
|
|
|
The push rod was my last ditch effort. I had a partner lightly push the brake for me while I held the MC and I could tell contact ws made immediately so i am assuming all is well there. Then I jacked the ass end of the car way up to make the MC level to bleed on the car even though it can't ahve any air in it after so many bleeds. Bled the whole system in order again while tapping on everything with a rubber mallet as suggested by another post. But nothing! I'm beat and fed up so I'm going to let my wallet take a beating in stead. If I owned a garage (heated) I would have more constitution for this but bleeding brakes every night after work is taking it's toll. Thank god I'm not married. So, my question now is dealership or local garage? I'm afraid the dealership will insist on new parts even though the hoses, junction box, and MC are all new and the power booster is fine. However, the local mechanic might be as lost as I am. What would yall do?
|
|
-
|
|
Man, I really do sympathize. I've never bled a 240 but I've bled other cars (and bikes) that just seemed to defy reason. But I hate to see you give up now that you've got all the parts installed; you're just a good bleed away from having it done.
It is possible that an air pocket is trapped somewhere. Are you still using the power bleeder? If so, you may want to try bleeding the system while your assistant pushes the brake pedal with the car running. The power bleeder is only going to generate a few psi. A relatively small pressure will compress an air bubble rather than push it down the line. Fluid can flow around the bubble and it will seem that all the air is out of the system when it is not. That master cylinder will create as much pressure as a leg can generate. When the vacuum assist is added, you will have a multiplier for the leg force generated. Now you will have upwards of 1500 psi pushing fluid (and air if present) through the system.
It may not work. There may be something else that I haven't thought of giving you grief with this car. But it's worth a shot before you have to drop more money on the project.
--
Mr. Shannon DeWolfe -- (I've taken to using Mr. because my name tends to mislead folks on the WWW. I am a 51 year old fat man ;-) -- KD5QBL
|
|
-
|
|
|
I had exactly the same problem, I re-moved my vacuum booster and m/cylinder. Re-installed and had pedal when turned off and no pedal when engine running. I would stand on he brakes and it seemed the pedal would fall to the floor and not much braking effect. The problem turned out to be increadibly simple. I'm not sure how it happened but the push-rod in the vacuum booster was out of adjustment (wound to far in) although I suspect my 3 year old son had some part in it. I did the same thing replaced m/cylinder, bleed system 5 times & even once at the distribution block. no difference. If you have a manual there is a scematic on how to perform this. If you need help pls post back and i'll look up the info.
Thanks Greg
|
|
-
|
|
|
Wow. I'm floored if this is it. I have beld my brakes so many times it defies sanity. I don't get it though nor do I have the info to adjust, so I need to bug ya some more to post what ya got. I can't tell you how much I appreciate it. Was wondering though, couldn't you just loosen the bolts that hold the MC to the booster a bit and then have someone toch the break to see if the push rod is correct? My theory is that the MC would get pushed forward the tiny bit the loosened bolts would allow when the brake was pressed. Not scientific or acccurate I suppose. Therefore, yep I would love if you could post info on push rod adjusment!
Thanks Greg!
|
|
-
|
|
|
Very good to know. Hopefully I will remember this when I get to the brakes on my project. Thanks for the post.
--
Mr. Shannon DeWolfe -- (I've taken to using Mr. because my name tends to mislead folks on the WWW. I am a 51 year old fat man ;-) -- KD5QBL
|
|
-
|
|
|
Here is a really dumb question: are ALL of the caliper bleed nipples at the top of the calipers... especially the rear ones? If not, somebody mismatched right and left caliper sides when they were rebuilt. This is a common issue, and I can assure you that bleeder nipples at the bottom of a caliper don't bleed air, just fluid. Gravity is at work here.
On our 245 while in park at idle, if I pump the brake pedal, I can change the idle speed of the engine, this is normal.
jorrell
--
92 245 245K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently in pieces
|
|
-
|
|
|
Also there is a stutter from the engine if I pump the pedal rapidly but this is a brand new MC so I don't think the seal and can be blown in the back.
|
|
-
|
|
|
Ickaruz,
I am not an expert on anything but I know a little about a lot of things.
I noticed in an earlier post that you had to replumb the brake junction box. Closely check ALL the fittings you removed/replaced with your fingers. You are looking for ANY sign of wetness. If (when) you find a wet fitting try tightening it a bit but don't over do it. Use your best judgement and don't damage the fittings. Pump the brake to see if the bubbles still come up. If that fails, try replacing the fitting. You will have to bend up another brake line to replace the one that leaks.
But, it is possible the junction block itself is the source of the leak; brass is soft. If you find the junction block to be the problem, and it still leaks despite your best efforts, you may have to replace it.
I am still waiting for a report from a friend about whether or not he was able to salvage damaged brass on his Amazon. If it worked there, it might work for you too. I will have him publish a full report on the board (if it works).
Once the system is sealed up you will have to bleed it one more time.
--
Mr. Shannon DeWolfe -- (I've taken to using Mr. because my name tends to mislead folks on the WWW. I am a 51 year old fat man ;-) -- KD5QBL
|
|
-
|
|
|
Will check junction box in the morning. I wiped everything down after second bleed and didn'tnotice anything when pumping but will check again. Thanks!
|
|
-
|
|
|
Another kookey idea. Could the pressure regulator on the power booster have anything to do with my issue?
|
|
-
|
|
|
Yep, it can cause the engine stumble you describe. But it is a check valve not really a regulator. You need to replace it because your diaphragm won't hold an even vacuum -- it will vary with engine vacuum -- causing the brake to be hard and then soft and the hard again. At any rate, it wouldn't cause bubbles in the master cylinder. Only air coming in as the compensation port is uncovered can do that. Bubbles + soft pedal = leak on pressure side of the MC.
--
Mr. Shannon DeWolfe -- (I've taken to using Mr. because my name tends to mislead folks on the WWW. I am a 51 year old fat man ;-) -- KD5QBL
|
|
-
|
|
|
OK, will replace the check valve. Cheap part so I like that advice. Another new MC then too. I'll have to send back the other new one, but I am wondering why the back seal would leak on a new MC.
|
|
-
|
|
|
No, no. I didn't mean the master cylinder is bad. Unless you have fluid escaping from the master cylinder I don't suspect it. I don't know what I wrote that lead you to the master cylinder. Check for leaks in the system. I am pretty sure you will find at least one wet fitting. Once you have the system sealed, if you have further problems, get back to us on the board.
--
Mr. Shannon DeWolfe -- (I've taken to using Mr. because my name tends to mislead folks on the WWW. I am a 51 year old fat man ;-) -- KD5QBL
|
|
-
|
|
|
O', I got ya. Will check all tomorrow (of course it will be raining on me as usual) and will get back to ya on my progress or lack there of.
|
|
-
|
|
|
...when pedal is pushed. Easy to mistake for bubbles when you suspect them.
Did you bleed in the recommended sequence?
Two separate systems. Book sequence is:
LR, LF upper, RF upper
then
RR, RF lower 2, LF lower 2
When power bleeding, a few pedal strokes may help dislodge bubbles, also rapping the calipers (and rear Proportioning Valves) as the bleed screws are opened.
Does either front caliper have a "dimple" or punch-mark at the top of the outer half, near the line where the two halves join? If so, that means the caliper was assembled wrong when rebuilt, and one of the 4 chambers will be impossible to bleed.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
|
|
-
|
|
|
Bleed ing in the right sequence and I'll check the calipers for mark. Never rapped on anything before bleeding but I will defititely enjoy doing it. It's pouring out now so I'm holding off to later.
|
|
|
|
|
