Is there a transmission doctor in the house?

[Twerp]

Okay, so here are the symptoms...

Recently, I've been having some issues with 5th gear in my truck. After coasting in neutral, it hasn't been re-engaging smoothly. Generally, at speeds below 40mph, it will go into gear with a little pop. No big deal, but maybe a little more resistance than I can recall from before. At higher speeds it will grind a little before going into gear. It seems to do fine if I put it into fourth and then to fifth before releasing the pedal. This is a recent problem that has popped up in the past week. I've also noticed that it tends to be worse as I get farther along my journey, but it's not much of a problem when I first start off. Also, on cooler days, it isn't as pronounced. I think it might be heat related. I got my transmission fluid changed about 2 months ago. I wonder if they put the right oil weight in or something like that. I hope I haven't worn out some part of my transmission by doing pulse and glide. With Toyota's legendary reliability, I'd imagine that it would take more than pulse and glide to wear out a Toyota manual transmission.

So, are there any Toyota transmission specialists out there that can advise me? Is it a matter of switching fluid weights? Checking fluid levels? Waiting for cooler temps to do p&g? Or could this be a serious problem in the making?

[Red]

I would check the fluid, make sure there is enough in the trans and the right kind. Else it sounds like a syncro related problem

[roflwaffle]

First things first, check fluid levels and make sure you have enough in there, as well as the right fluid if possible. Aside from those two, depending on how many miles and how much shifting you've done it could be the clutch is going or your fifth gear synchros aren't engaging right for some reason.

[lovemysan]

Is this a manual trans. If so does the manual spec a GL4 rated fluid? I find it a real common issue that mechanics will put a GL-5 trans oil in a GL 4 rated unit. The problem is that GL-5 fluid will corrode yellow metals. Often synchronizers are made of yellow metals. It sounds just like what happened to inlaws nissan pickup. Changed fluid and in a few months 2nd gear started to grind even shifted slowly.

I've used redline mt90 (spec'd replacement for 75/90 gear oil) for my nissan, it will improve the shift quality. You can call redline's tech and get them to recommend which of there fluids to use.

[lovemysan]

You could also have an issue with the slave cylinder or clutch master cylinder. If its not fully engaging the clutch then you get the hard to shift feeling.

[jesse.rizzo]

I'll have to add another vote to the synchro idea. One easy thing to do is simply match the RPMs, with it in neutral and the clutch out, then shift back to 5th. The synchro doesn't have to do anything.

[Whoops]

The problem your describing is the syncro for 5th gear is worn out and giving you warning signs. The coasting in neutral, then putting it back into 5th gear, requires the 5th gear to be spinning at a speed to mesh without grinding. When you push on the gear shift, the resistance you feel is the synchromesh engaging. Every time it engages, it wears a little on it.

If the transmission oil is low, it will cause the syncro to wear out extremely fast. I would check or have the oil level checked. If you use to light of an oil, it will cause it to wear faster than not.

You can change the oil to a heavier weight oil, with a slight, probably not noticable difference in mileage and it will help some.

Although the transmission has to be pulled to have the syncromesh portion replaced, it is driveable as it is and if you don't mind, you can work around it, virtually indefinitely.

First, if you match the engine speed to the drive line speed, the gears will be already spinning at the correct speed to mesh properly. You can feel this point, occasionally, if you try to put the car in gear without depressing the clutch and the gear shift is able to move the gears to engage, without having the clutch released. The problem with this is that you have to match the drive speed and the rpm, for it to work. However, the same principle works even if you depress the clutch, if the rpm and drive speed are matched the gear can be engaged with little or no syncro work.

The other alternative is that if you shift into 4th, that uses the 4th gear syncro to spin the gears and get them to pretty close to the correct speed. If you then shift it into 5th, the 5th gear syncro doesn't have a lot of work left to do.

Early automobile manual transmissions did not have syncros. Instead, as the operator, you had to depress the clutch, shift into neutral, engage the clutch, speed up the engine to the right rpm, depress the clutch, shift into gear and then reengage the clutch. This technique required a certain amount of art/skill to estimate the correct rpm, to go with the speed being driven and the gear being selected. When it didn't get done correctly, you would end up grinding gears. When you didn't do it properly, very often, you'd blow out the transmission gears with chipped teeth and metal filings.

When you do the neutral coasting and gear reengagement, it puts a strain on the syncros. In my personal perspective, in and of itself, transmissions are far to big a repair job to fool around with saving a few cents in mileage, at the expense or potential expense of the transmission. Other people may feel differently.

[Twerp]

Hmmm... These are all very good theories... Here's the info that I'm going to come away with: It's worth checking the transmission fluid. I do have a stick shift and according to the owner's manual, it takes API GL4 or GL5 gear oil with a viscosity of 75W-90. Not sure what Valvoline put in there, so I'll have to try and check on that. Perhaps flushing my transmission would be a good idea. Or at least running some sea foam through it before I drain it to change the fluid.

It sounds like my 5th gear syncro might be worn. Toyota generally builds things to last though and I haven't heard of other hypermilers having this experience, so I don't know if P&G is 100% of the cause. It may be a contributor but I would suspect the oil first. Another possibility that I thought of might be that the previous owner might have skipped a service interval and there might be some sludge in the transmission but I don't know how likely this is. I'll have to double check my maintenance schedule to see when the intervals are.

I will prolly start using the fourth gear syncro to get it into fifth gear at speeds over 40. If I start having problems with 4th, I will know to just give up on P&G and look for other methods of saving gas... Just out of curiosity though, does anybody know the approx cost to get a syncro replaced? I'm guessing in the $2,000 ball park. How far off am I?

[Red]

If the syncro is gone, I'd just get handy with double clutching. Since it is 5th you don't shift in and out of it that often to be a major problem. Much easier to life with having the syncro gone on a higher gear than it is on a lower, like 2nd on my Insight

[lovemysan]

Originally Posted by Twerp

Hmmm... These are all very good theories... Here's the info that I'm going to come away with: It's worth checking the transmission fluid. I do have a stick shift and according to the owner's manual, it takes API GL4 or GL5 gear oil with a viscosity of 75W-90. Not sure what Valvoline put in there, so I'll have to try and check on that. Perhaps flushing my transmission would be a good idea. Or at least running some sea foam through it before I drain it to change the fluid.

It sounds like my 5th gear syncro might be worn. Toyota generally builds things to last though and I haven't heard of other hypermilers having this experience, so I don't know if P&G is 100% of the cause. It may be a contributor but I would suspect the oil first. Another possibility that I thought of might be that the previous owner might have skipped a service interval and there might be some sludge in the transmission but I don't know how likely this is. I'll have to double check my maintenance schedule to see when the intervals are.

I will prolly start using the fourth gear syncro to get it into fifth gear at speeds over 40. If I start having problems with 4th, I will know to just give up on P&G and look for other methods of saving gas... Just out of curiosity though, does anybody know the approx cost to get a syncro replaced? I'm guessing in the $2,000 ball park. How far off am I?

I would change it to the redline mt90 and see if it helps. I suspect it will.

Carpart.com and request a bid for your transmission. I'd say you could rebuild or replace for less than $1500.

Flywheel surfacing $50
clutch kit $150-300
tail seal $15
used trans $700?
labor $250?