QuestionQUESTION: Howard, you really seem to know how to answer questions clearly!! Hopefully this one is easy.
I bought this 1975 MGB in 1980!! I have it twenty seven years but it was on the road for only three years. I took it off the road in 1983!! As you would expect,the engine froze and everything dried out and rotted except for the body and the interior. I just had the engine rebuilt and replaced every and anything rubber, brakes, lines, etc. I finally got everything together and the newly rebuilt engine running but...the new clutch master cylinder and slave do not seem to be working. I am pretty good with this stuff so I think there might be a trick to getting it going. I replaced everything, the Mast cylinder, pipe, rubber hose to slave, slave and everything else but the yoke. When I open the bleeding valve and have someone pump the pedal the brake fluid runs out the bleeder valve (through a hose) and it looks clean (no air bubbles). I make sure the reservoir does not empty but when I tighten the bleeder valve closed and I press the pedal the slave does not push the rod into the yoke. I checked my fitting and they seem to be tight with nothing leaking. Is there a trick or do you think the slave, while brand new, is defective? Your help would be appreciated. I am 53 years old and want to get this car of my youth back on the road so I can feel like I am 26 again!!
ANSWER: Hi Robert,
The slave cylinder is nothing but a cylinder with a piston and one seal, the only thing that can be wrong with the slave is for it to leak. Your problem is either the master cylinder or you are not getting the air out.
Do this, make sure the reservoir is only half full and take a pry bar and force the clutch arm and slave cylinder rod back into the slave cylinder all the way. This forces the fluid in the slave back up into the master and on into the reservoir. Now, push the clutch pedal all the way down to the floor, then let the pedal up VERY slow. When the pedal is all the way up push it down again and again let it up VERY slowly. The reason you let it up slowly is because the hole from the reservoir into the master is very small and if you let it up quickly the spring in the master will force the piston out too fast which allows new air to bypass the seals and take new air into the system. You may have to use the pry bar several times to force all of the air up into the reservoir. let me know.
Howard
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QUESTION: Howard, I got it to work. I ended up using a C-Clamp to squeeze the piston in and had a person press the pedal as you instructed. I had to do it a few times and each time I did it the stroke got longer until it went the full stroke.
There is NO WAY I would have EVER figured this out.
Thanks so much!!
Here is an easy one, on my 75 MGB the timing pointer on the timing chain cover do not indicate how many degrees each point is. Do you know?
Thanks again!!!!!!!
ANSWER: Your welcome Robert, 5 degrees between each pointer on the 75 B.
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QUESTION: Howard, I can't help myself, I have to ask you a couple other questions, not critical but inquisitive. I guess the clutch piping is bigger because it exerts more P/S/F than a brake? Curious on that one.
I just had the engine rebuilt and got it started this weekend. It has about 20 minutes of running time so far. The guy who re-built it said to run it for about 15-20 minutes at 1800 RPM then change the oil and filter to get all the other lubricants he uses when he assembled the engine out. Then the car is ready to go.
I am finding that when it isles at 1800 rpm it blows smoke (not a lot but enough to make me think) out the tailpipe. I have no reason to think the engine was not rebuilt properly as the person is a pro and it is his business (i.e. not a hobby plus he came recommended by MG mechanics). The question is, will the engine smoke a little until the parts work themselves in and the oil is changed a few times? Or is any smoke already an indication of a possible problem?
Plus, the valve clatter like crazy even after warming up. I am pretty sure this car has solid lifters so it is not like the hydraulics have to get filled with oil before it quiets down.
I am thinking that the rebuilder could not do a warm engine valve adjustment and I will need to do that before they are quiet. Thoughts?
What do you recommend in the "breaking in" period for a rebuilt engine?
Thanks again!
AnswerThe clutch line is larger because it has to move a larger volume of fluid.
Smoke after a rebuild may be normal for a while, depending on what kind of rings were used and if the cylinder walls were deglazed (if just rings were installed).
On an engine rebuild the only things that require a brake-in period is the rings. You need to note the color of the smoke. Blue is oil, white is coolant and black is excess fuel.
The recommendations he gave you are good. I would just add another oil and filter change at about 500 mi. and I tell all of my customers to not apply a load to the engine below 2000 RPM and not to exceed 3500 RPM for the first 500 mi and then only increase the RPM available in gradual increments over a period of time. Always change filter with an oil change and never go much beyond 3000 mi on a change. Keep the ignition timing set to specs. Always warm up an engine before driving.
Watch oil pressure and coolant temp. If you are on an expressway and you see the temp hot you have minutes before you have major engine damage. If you see the oil light on and the gauge reads little to no pressure, you have seconds before major damage is done.
If you have blue smoke on accelertion, note the amount and check it every few hundred miles and note that it should be getting less. If you have a CAT in the exhaust you should remove it until the smoke clears up (about 300 to 1000 mi)
You can test the engine yourself with very few tools if you are worried about the rebuild. Read my tech tip on engine tests. http://mg-tri-jag.net/tech9.htm
Noisy valves were a normal problem we had at dealerships so we set the valve clearance down to .012 in on intake and exhaust. It was more quiet and we noted the clearance stayed for a longer period of time. I believe BLM made an error on the transition ramps on the cam.
Yes, all MGs had solid lifters.
Don't mix up valve noise with what is sometimes called "valve rattle" (the pinging noise on a quick acceleration) True valve noise is the same at idle as it is at higher RPM, just faster.
Pinging on acceleration is a very dangerous (to the engine)and must be corrected right away. It has nothing to do with valves.
Good luck, let me know how it works out.
Howard
