Guest Posted March 31, 2005 Share Posted March 31, 2005 I've got a 1972 monte with a th350 and it shifts into first and second fine but it wont shift into third ever. even when I have it maxed out. My dad fills it up with tranny fluid often. Also if the shifting problem is something to do with the vacuum modulator, then can that be related to why sometimes my engine only runs on 7 or 6 cylinders sometimes? Thanki very muchi Quote Link to comment Share on other sites More sharing options...
wallaby Posted April 1, 2005 Share Posted April 1, 2005 Welcome to the boards! There are a great bunch of guys here that can help with almost any issue. The modulator could cause your problem. That's the easiest thing to check anyway. Make sure the vacuum line is connected at both ends. If you have a broken or leaking vacuum line going to the modulator, it will cause the trans to shift weird and the engine to miss at lower speeds. Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted April 23, 2005 Share Posted April 23, 2005 I've got a 1972 monte with a th350 and it shifts into first and second fine but it wont shift into third ever. even when I have it maxed out. My dad fills it up with tranny fluid often. Also if the shifting problem is something to do with the vacuum modulator, then can that be related to why sometimes my engine only runs on 7 or 6 cylinders sometimes? Thanki very muchi Spencer, I'm comfused, you're saying that while in drive the xmsn will not up-shift to third..correct me if I'm wrong but it should shift only twice..I don't think while in drive it'll shift 3 times,unless you're saying that.. you can't manually shift it!!  Rod  Quote Link to comment Share on other sites More sharing options...
Kliegl Posted April 23, 2005 Share Posted April 23, 2005 . Quote Link to comment Share on other sites More sharing options...
Guest Posted April 23, 2005 Share Posted April 23, 2005 k it is a 3 speed tranny so it will shift into first shift into second and it will not shift into third. on my shift consol it goes P,R,N,3,2,1. I put it into third to drive shifts into 1 shifts into 2 and not into 3. Quote Link to comment Share on other sites More sharing options...
Guest Posted April 23, 2005 Share Posted April 23, 2005 When you start out in Drive the tranny is already in first, it doesn't have to shift into first so you should feel the second shift and the third shift, 2 shifts not 3. Hope this makes sense. Quote Link to comment Share on other sites More sharing options...
superstk Posted April 23, 2005 Share Posted April 23, 2005 I think what your saying is you have 1 gear(low) and it works. 2 gear(low 2) and it works. But when putting it in drive it doesn't engage? If that's the problem, look at your linkage with someone shifting the gears(in park, engine off). See if the linkage is engaging drive(D). If not, you may have to adjust the linkage or replace it(may be worn out). Hope this helps. Fred Quote Link to comment Share on other sites More sharing options...
superstk Posted April 23, 2005 Share Posted April 23, 2005 Running on 6 or 7 cylinders usually means, you need to get new spark plugs and/or sparkplug wires. If your running the car in low 2 and winding the motor out trying to maintain a high speed (beyond 45 mph) your over reving your engine!Low 1 is usually good to 15-25mph, low 2 is usually to 45mph. Different situation if your running a racing tranny. If you leave the car in drive(D) you can't get it into drive(D)? REally sounds like you have a linkage adjustment problem. Fred Quote Link to comment Share on other sites More sharing options...
Guest Posted May 5, 2005 Share Posted May 5, 2005 to start off my drive gear is 3 on the consol. when i put it in 3 it shifts into 1 gear. and when time it shifts to second and then will not shift to third Quote Link to comment Share on other sites More sharing options...
Guest Posted May 9, 2005 Share Posted May 9, 2005 Hey Hey Spencers Ok I hope you can get this If you had a 3 soeed stick tranc you only shift 2 times you put it into 1st and then go to 2ed and then to 3rd and if it was a 4 speed then you would go into 4th 3 shifts so if your tranc is shifting 2 times it is going into 3rd. I hope this helped Dave Quote Link to comment Share on other sites More sharing options...
Guest Posted May 10, 2005 Share Posted May 10, 2005 yes i know that ive been told and thats not the problem. Let me put this staight forward It does not shift into third thanks Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted May 11, 2005 Share Posted May 11, 2005 Spencer,  I don't think you seem to understand, that your Monte Carlo with a TH350 will not shift (3) three times, because it will shift (automatically) only twice! It will begin in (D)(first forward gear where you place your car in) for it to move forward, it'll proceed into (2nd) forward gear and shift finally to (3rd) foward gear! Therfore only shifting twice. Don't get upset if you can't get it to shift three times because, it wont.  Rod  Quote Link to comment Share on other sites More sharing options...
Bob Hansen Posted May 14, 2005 Share Posted May 14, 2005 Ok I'll chime in here too. Â The modulator controls all shifts, since it shifts from 1st to 2nd and not from 2nd to 3rd it is not a modulator issue. Â I think what he is saying is that when he places the shifter in D the trans engages (shifts) into first gear, then once under way it will shift up to second but will not make the leap to 3rd. Â One possibility is that someone has put a PowerGlide (2 spd) trans in the car. Â Another clue is "My dad fills it up with tranny fluid often" If the trans leaks when the fluid gets low, the pressure on the plates drops, they slip and wear out. Typically when a TH350 is on it's last legs, Drive (3rd) quits working and reverse starts to slip (3rd & Reverse use the same clutch pack) then reverse goes. I have seen TH350's continue to function on just 1st & 2nd long after drive & reverse failed. Quote Link to comment Share on other sites More sharing options...
Guest Posted May 14, 2005 Share Posted May 14, 2005 ya sometimes reverse doesn't work. were is the vaccum modulator located? Quote Link to comment Share on other sites More sharing options...
Guest Posted May 14, 2005 Share Posted May 14, 2005 and also how can i fix that problem? new clutch plates? or a simple fix? thanks Quote Link to comment Share on other sites More sharing options...
wallaby Posted May 15, 2005 Share Posted May 15, 2005 I dunno....it sounds like you have all the clues to point you to a bad modulator. You have shifting problems, you have a loss of trany fluid, and you have a dead or weak cylinder in the engine most noticeable at idle. It sounds like the modulator has ruptured and is letting the engine suck your trans fluid out thru the vacuum hose. In my experience, the bad modulator will give you a shift from first to second, but it is delayed and happens at a higher RPM than you would expect. Ditto for the shift from 2nd to 3rd...in fact it will be delayed so far that you might think the engine will blow up before the trans will ever shift. With no vacuum signal to the trans the broken modulator is telling the trans that the engine is running at wide-open throttle and even though it isn't....the trans behaves as if it is. The TH350 is a little different and uses a cable for the kickdown function and I wonder if that could be misadjusted and cause the shift problem? None of this has anything to do with reverse. Lets hope that reverse is stubborn only on the days when the fluid level is low. Quote Link to comment Share on other sites More sharing options...
Guest Posted September 18, 2005 Share Posted September 18, 2005 Were does the hose from the modulator go to? If it is a bad modulator how do I get it off? Can I buy a new modulator at a local parts store? Quote Link to comment Share on other sites More sharing options...
Grease Posted September 19, 2005 Share Posted September 19, 2005 On a Turbo350 the vacuum line should be a metal tube from the intake manifold ... right behind the carburetor.it would have a short piece of rubber hose to attach it to the manifold fitting.it would normally be clipped along the oil fill tube to the trans . the modulator is at the rear of trans right side. the metal vacuum tube would again be attached to the modulator with a short piece of rubber hose. Â the modulator is held in place by a clamp with a bolt .remove the bolt and the valve should pull out( twisting might help). should have an o-ring seal on it . the auto parts stores should carry them. Â i would replace the rubber hose on each end , as it could cracked or hard and brittle . it is after all 33 yrs old . Â i would also have a drain pan under when replacing it ...might leak a bit . Â mike Quote Link to comment Share on other sites More sharing options...
kc8oye Posted September 21, 2005 Share Posted September 21, 2005 Wallaby gets my vote.. change the modulator.. they're $10 at autozone.. check the hoses too.. also.. unplug the modulator vacuum line and plug it.. see if the idle improves.. Quote Link to comment Share on other sites More sharing options...
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