Many atempts to solve problem with M5OD, one solution wich work
Maybe is to late to reply for steelynirvana, but i don't see this post before.
I have similar problem for long time. In summer (here can reach 40 oC) I have problem to get in first and reverse, and sometimes also have grinding noise at the moment prior engaging third. Mostly i solved problem with going in to second than first, than fourth -first and so. Even, when is very hot and stuck in traffic, also must keep clutch pedal down because it was impossible to put in first or reverse without stopped the engine
Because I already have problem with my slave cylinder (which I posted earlier), first I change with new one together with clutch disk. Next hot occasion same problem. I change ATF in tranny with original Ford Mercon ATF ,but only minor improvement.
Maybe clutch fluid is boiling? OK -Changing with Motorraft super DOT 4.
Result: nothing change.
Then I got serious impulse to solve problem.
In warmest day ,I warm engine and gearbox, and immediately go under the explorer with helper to press clutch pedal and check did slave cylinder work and how much travel it do. Wait to cool and do the inspection on cold engine and gearbox. Engaging and traveling of the slave cylinder was same . So problem is not in the clutch hydraulic (master or slave cylinder or fluid)
Because in that moment I have 392.000 kilometers, maybe is clutch pressure plate (the spring is changing characteristic with temperature, became weak and don't disengage the clutch disk?)
OK. I order new clutch set (pressure plate,slave cylinder, disk, flywheel bush). Prior to instal new one in to explorer, I check and compare new pressure plate with original one (pressure to work,travel to disengage and so) Results was practically the same, with minor difference, but because a checked in cold status, I proceed.
With everything new (except master cylinder) I go in to hot "situation".
Result: nothing change.Nothing at all.
In that moment I was sure that problem is not mechanical, but physical.
In other word, problem is in ATF fluid which , when is hot, don't have enough viscosity to make friction to synchronize speed.
So I do experiments with lot of ATF : Motorcraft Mercon, Motorcraft Mercon V , Valvoline Mercon, Valvoline Mercon/DextronIII, Sheel Heavy Duty ATF, Castrol heavy duty ATF,blend with viscosity enhancer, even make own blend with ATF and 10% GL4 hypoid 80w, ATF and 20% GL , hypoid 80w , with some results.
And than I put Liqui Moly ATF III with Mercon and Dextron III specification. I don't expect to much because its viscosity and thermal characteristic was worse than heavy duty ATF's characteristics,
Problem dissapear!! Completely.
First and reverse? Like in the butter with two fingers, nothing grind, nothing push back ,nothing hesitate, in other words perfectly.
For me in that moment it so unbelievable, that I start to think that something else is changed.
So I drain that ATF and put Castrol Heavy Duty ATF (with which I have best results before) and problem is come back,
Change again to Liqui Moly and problem again disappear.
After 35.000 km I notice some minimal resistance to go into reverse in hot situation. I don't wait, change with fresh ATF , and again problem disappear. After new 40.000 km same indication, same solution.
Now my explorer have 493.800 km, and clutch and gearbox is working perfectly
So conclusion:I don't know what in that particularly ATF is working so well with M5OD, or why the others which I try don't. I certainly don't believe that only that ATF is ideal for M5OD. But,also I never expect that gearbox, in my case synchron's in gearbox , can be so sensitive to ATF.
I never have chance to check with other ATF (Amsoil and so). but after all I don't need to check
Because I see to many post with similar problem, and most of the people think that slave cylinder is causing problem, I make so long reply with all my attempts to solve the problem.
I certainly think that, in case of similar problem, it is very clever to check did the slave cylinder work properly (thru opening in bell housing), and if is work, to try solve the problem with changing ATF (in any case that is cheaper)
