New Qs: Clutch hydraulics, Lift pump, MF switch

[purvisgs]

Hi, newbie to nissans, but not small diesels, thanks for all the good info here, I have been searching the forum a lot and this has allowed me to work out many of the little quirks in my new 84 sd25.

Most frustrating was to spend $100 on new glow plugs only to have them all burn right out because relays were not shutting off. Second set of glows and bypass switch for now powering relays so even afterglow works, I just have to hold switch in... a few things are proving to be really frustrating still (I ordered a fsm, but it's not here yet).

First of all, turn signals went out slowly on me, gradually slowed down to nothing, switched turn signal and hazard relay and both work in hazard position. So I suspect turn signal switch (part of MF Switch) on column to be bad. Mine is the type shown with green wires going to plug as in this thread: http://nissandiesel.dyndns.org/viewtopi ... =7030#7030

I can see in there fairly well and don't see any obvious signs of burnt contacts or bad wires/ etc. By turning the turn signal "handle," it looks like I am moving some sort of switch in the correct manner. No signs of broken plastic.

I have all the plastic, horn, etc, off, but can't figure out how to remove the steering wheel or column in order to slide the plastic mf switch off. tried loosening big nut on wheel, pulling with a puller but no luck/ couldn't get a good grip. So, a quick description of how to get to the point where mf switch will slide off would be very greatly appreciated.

Next thing is the clutch hydraulics. When I push pedal to floor and is cold, it barely (if at all) disengages. It gets better when warm. I suspected the clutch damper was not working correctly so I replaced the rubber disc behind the metal plate with nylon washers per Philip's advice on this: http://nissandiesel.dyndns.org/viewtopi ... ght=clutch . No real improvement. I bled the lines to look for air. Pedal play seems to be adjusted ok.

If I look at the transmission while someone steps on the clutch, it seems that fork doesn't move as much as it could / should, so I am very hopeful this is just hydraulics and not something more significant.

I know that several threads have suggested against it, but I would like to try to bypass the damper and see if this gives me more play before I go ahead and replace the slave/ then master cylinders (based upon prices that local parts store has quoted me for these).

A few questions about this choice:

-could I pull master/ slave cylinders out of gas nissan pickups/ other nissans / (what years?) at junkyard?

-I don't much care about pedal chatter/ etc/ if I do bypass damper and say my slave is starting to go out or partially bad (I suspect slave because of location over master being bad). would i really get up to an extra inch of play (read this in another thread somewhere, can't find it now), or would this just make the (suspected bad) slave cylinder go bad all the way more quickly?
-what fluid does fsm suggest?

Next, the lift pump does not work due to (i suspect) missing primary (screen) filter. I currently have it bypassed with a quality electric pump. I know how some of ya'll feel about electric pumps, don't worry, this is just temporary...

I have not removed the old lift pump however, and worry about possible damages running it like this (i know for example chevy diesel lift pump can be bypassed w/ electric, if you do this you can get from the dealer a "block off plate")

I don't see any signs of oil leaking/ etc, but it just doesn't seem like a good idea to run it (even at all) with just 2 open fuel pipes collecting dirt.
-is there a block off plate available/ should i make one/ should i not worry if i plan to replace the lift pump in the next 1000 miles?

Finally, a relay was seeming to make contact and disengage randomly sometimes, located under the passenger seat. do you know what this relay might be?

THANK YOU!!!

[asavage]

first of all, turn signals went out slowly on me (gradually slowed down to nothing), switched turn signal and hazard relay and both work in hazard position, so i suspect turn signal switch (part of MF Switch) on column to be bad.

The HL switch portion of the MF switch is the part that gets the most abuse. I've never heard of the turn sig switch going bad (yet).

In the turn position, do the front & rear lights stay lit (and just not blink off)?

You can connect a replacement MF switch without installing it to the column, to test the new switch.

I have all the plastic, horn, etc, off, but can't figure out how to remove the steering wheel or column in order to slide the plastic mf switch off.

I've removed about a dozen at JYs (where I am not putting it back together) and have put the nut back on loose and whilst pulling hard up/out on the wheel, whack the nut. Hard on nuts, hard on the shaft, but it's a JY . . . and the wheel always comes off (on Datsuns).

I can't recall, but aren't there two tapped 8mm holes in the wheel's hub? Yes, page ST-3 in the 1982 FSM shows the std. layout. Use a steering wheel puller (not a harmonic balancer puller, whose hub is too large to allow the narrowly-spaced bolts to fit correctly). A cheap puller is under $10 at your FLAPS. Good one will run under $30.

Next thing is the clutch hydraulics... I push pedal to floor, when cold it barley (if at all) disengages, better when warm . . .

This will not be a slave cylinder. You will have to replace the clutch master cylinder. It's not as bad as it appears, really. Yes, you have to get your head under the dash, but it only requires two 12mm wrenches, a 1/4" drive 12mm deep socket and extension, and a pair of pliers, IIRC.

The master is not building pressure in the first part of the stroke.

a few questions about this choice:
-could I pull master/ slave cylinders out of gas nissan pickups/ other nissans / (what years?) at junkyard?

Spending a minimum amount of time with NAPA online, it looks like the clutch master cylinders are pretty much all the same, gasser, 4WD, diesel.

Finally, lift pump does not work due to (i suspect) missing primary (screen) filter. I currently have it bypassed with a quality electric pump.

The OEM lift pump runs much higher pressure than any electric aftermarket. Will work short-term though.

I have not removed the old lift pump however, and worry about possible damages running it like this .

Could use a loopback line (line from in to out) filled more or less with diesel.

Or you can pump the fuel through the lift pump, if it isn't leaking.

is there a block off plate available/ should i make one/ should i not worry if i plan to replace the lift pump in the next 1000 miles?

No, no, and maybe.

Can't guess at the relay noise under seat.

Off to work.

[purvisgs]

sorry, this post might have been better off split into 2 threads, 1 under support sys, 1 under engine forum... hope this is ok

In the turn position, do the front & rear lights stay lit (and just not blink off)?

Nothing happens at all when i flip the lever to the turn position...

No power to relay location as tested by voltmeter, also switching turn relay to hazard position, hazards work so relay is ok.

This leaves wiring and switch...

No obvious signs of tinkering or damage to wiring harnesses in this area.

It looks like I may be able to just unscrew(see picture linked to above, 3 or so brass colored philips screws) "turn" portion of the switch from mf switch (without taking off wheel), I didn't want to attempt this though because parts could fall out / I don't have much visibility in there to know how they might go back together.

Will try the local junkyard for a switch and try to plug it in externally, thanks for the suggestion. If I can't find one, (Al), would you happen to still have the newer (green wires to plug) type of spare that you might be willing to part with?

Don't yet have a wiring diagram for the pigtail that plugs into mf switch (green wires for turn signal), wiring diagram would help me better troubleshoot, but would have to be specific to newer version with pigtail and plug-in

Thanks for suggestion on looping in/ out lines to lift pump with loop filled w/ diesel...

As far as I can tell, I can't pump through it (I tried this first) very little fuel is getting through...

It also looks like (based upon draining bottom of tank) I may have to drop tank to fully clean it. Lots of junk + rust .

So I believe lift pump may be plugged/ clogged.

Running a tank of 50% bio-d (solvent) with no primary filter protecting lift pump obviously is what caused it to go bad. lots of junk + rust in tank (based on draining bottom), I may even have to drop tank to clean it properly, we will see how many filters I clog.

I don't have a good understanding of the lift pump design yet/ but it is not letting much of anything through, not leaking fuel externally

Don't worry, secondary filter has been changed and is protecting IP.

[philip]

Hi, -snip- ... my new 84 sd25.

Most frustrating was to spend $100 on new glow plugs only to have them all burn right out because relays were not shutting off. Second set of glows and bypass switch for now powering relays so even afterglow works, I just have to hold switch in... a few things are proving to be really frustrating still (I ordered a fsm, but it's not here yet).

Refer to Al's handy Factory Service Manual for
Electrical - Glow system. There are 6 pages total. Use the Back-Next toggle.

SNIP

Next thing is the clutch hydraulics. When I push pedal to floor and is cold, it barely (if at all) disengages. It gets better when warm. I suspected the clutch damper was not working correctly so I replaced the rubber disc behind the metal plate with nylon washers per Philip's advice on this: http://nissandiesel.dyndns.org/viewtopi ... ght=clutch . No real improvement. I bled the lines to look for air. Pedal play seems to be adjusted ok.

If/when you loose your pedal over-night or when you think you've gotten all the air out of the brake fluid and ... still have no pedal pressure, then replace slave cylinder assembly.

SNIP-
A few questions about this choice:

-could I pull master/ slave cylinders out of gas nissan pickups/ other nissans / (what years?) at junkyard?

I bought my NEW Master Cylinder for $35. The Slave Cylinder cost me $18. What's your time/$ worth?

SNIP-

-SNIP-
I have not removed the old lift pump however, and worry about possible damages running it like this (i know for example chevy diesel lift pump can be bypassed w/ electric, if you do this you can get from the dealer a "block off plate")

The two banjos (entering and exiting) have a very small screen cup. Pull these out (easy), clean, reinstall. While the engine is idling, you must feel suction on the 'entering' banjo and pressure 'exiting' banjo If either are defective, replace the entire lift pump. I paid $100. The forum does have a useful 'title thread' about the matter.

[asavage]

Refer to Al's handy Factory Service Manual for
Electrical - Glow system. There are 6 pages total. Use the Back-Next toggle.

I forgot I had some 1984 info up. I only remember the 1982 stuff.

If/when you loose your pedal over-night or when you think you've gotten all the air out of the brake fluid and ... still have no pedal pressure, then replace slave cylinder assembly.

I disagree. If air is purged and can't get full stroke, bad MC. A failed slave can only fail in two ways: seized, and leaking. If leaking, air is not going to get in and change symptoms on you. Go for the MC first.

I have "lots" of MF switches. I get $20 for them, but they are untested. I can send you two and you return the one you don't use. [later] Well, I do have an '86 PU outside, but I'd have to drag a battery out to it . . . if you want me to test one, I guess I could pre-test it before shipping.

But around here, JYs are full of them. I don't know where in "WA" you are, but the Pick-A-Part in Lakewood (Tacoma) is where I go most (MF switch is ~$9), and they always have 720s for the picking. Sometimes the late ones, sometimes the early ones. It is kind of miserable this time of year though.

[asavage]

It also looks like (based upon draining bottom of tank) I may have to drop tank to fully clean it. Lots of junk + rust .

Running a tank of 50% bio-d (solvent) with no primary filter protecting lift pump obviously is what caused it to go bad. lots of junk + rust in tank (based on draining bottom), I may even have to drop tank to clean it properly, we will see how many filters I clog.

While I've heard several people state that changing to BD would "clean out" the fuel system, I've moved several diesel vehicles to B100/B99, and not only never had a filter plug, I've cut open filters looking for excess crud and not found any. I'm thinking that many of the tales of filters plugging may be due to the fuel not meeting ASTM D-6751.

----------------

I've got three 720 diesel fuel tanks in storage, and I'm only going to need one of them for the 1986 gasser->SD conversion. See this thread for some pics. There are several different tanks, but I suspect many are interchangeable.

The diesel tank should be different from the gasser tank, in that diesel does not get along with the zinc (galvanizing) in gasser tanks. If you don't want to deal with cleaning and re-sealing your tank, I can fix you up with one of my extra diesel fuel tanks. You'll want to crawl under and measure the length first.

[asavage]

In the turn position, do the front & rear lights stay lit (and just not blink off)?

Nothing happens at all when i flip the lever to the turn position...

No power to relay location as tested by voltmeter, also switching turn relay to hazard position, hazards work so relay is ok.

This leaves wiring and switch...

Referring to the 1984 720 FSM, Turn Signal schematic & wiring diagrams, the current path is:

• Battery
• Fusible link (connector 23M)
• Ign. switch (connector 97M)
• Fuse block
• Yel/Red wire to flasher relay, Green wire out
• Hazard switch (connector 109M), Green wire in, Grn/Wht out.
• Turn signal switch (connector 104M), Grn/Wht in, Left = Grn/Red out, Right = Grn/Blk out.

I would check the output of the Hazard Switch first. If that's good, check the output of the Turn Sig Switch. You might find that the Hazard Switch isn't passing on voltage to the TS Switch.

[asavage]

Finally, a relay was seeming to make contact and disengage randomly sometimes, located under the passenger seat. do you know what this relay might be

Referring to the 1984 720 FSM, Location of electrical components, the only things I see that could click in that area are the cruise control unit ("ASCD") and the dome light timer, both under the passenger seat.

If your truck has power door locks, there's a relay for it shown on the next page (EL-95). It's in the side panel behind the pass. door.

[philip]

Refer to Al's handy Factory Service Manual for
Electrical - Glow system. There are 6 pages total. Use the Back-Next toggle.

I forgot I had some 1984 info up. I only remember the 1982 stuff.

That's because you know everything while I ... remind you.