Small overheating problem

General information about the first-generation Nissan Maxima in the US. What was the Datsun 810 became the luxury leader Maxima in the US in 1981.

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kassim503
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#181

Post by kassim503 » 12 years ago

I just remembered another reason she might be idling bad when warm, intake leak. I gotta whip out the carb cleaner and shoot around after I run to the parts store to update the ignition.
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

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kassim503
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#182

Post by kassim503 » 12 years ago

Figured id put this problem up in this thread cause it seems to be the thread of all the problems that I encounter with my gasser

I took the maxima out for a ride around the block, to see how shes feeling and to get some of the snow piled on it off, and after pulling away from a intersection and getting up to speed i got to overdrive and started chugging along, then the trans shifted from 4th to 2nd after depressing the gas pedal a very small distance farther in. I wasnt even close to the kickdown switch or nothing. After a 200 feet or so it shifted back down, and it did it a couple of more times in and out with small changes in the gas pedal stepping on it more and one time letting go. I drove it around for another 5 minutes and it didnt repeat it after the minute or two of the sporadic shifting.

Anybody got any clues? My guess is snowy and wet feet got water on the kickdown switch and the water froze in the switch and it was reluctant to sliding back out. Or a broken vacuum modulator hose, only hunches I got.

The forecast is snow for the next week or so according to the forecast, so I am trying to diagnose it from inside, gonna crack open the fsm and read up a little instead of being outside and becoming a snowman.
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

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asavage
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#183

Post by asavage » 12 years ago

The kickdown switch is above the accel pedal, inside the car and right next to the heater, so I doubt it got water in it and stuck. A broken modulator usually affects the whole range of shifts, so if it downshifts too soon, it should upshift too high as well.

I don't have a good guess on this one yet.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

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kassim503
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#184

Post by kassim503 » 12 years ago

it sucks how the symptoms went away, im gonna try sealing the exhaust temporarily tommorow and try driving her till the trans fluid makes the 0-180F range and listen for abnormalities.

I dont think my feet even fit in the vicinity of the switch, there is only a tiny probability that would actually happen. Btw I didnt have the heat on, I only drove enough for the t-stat just to open barely
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

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asavage
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#185

Post by asavage » 12 years ago

kassim503 wrote:. . . driving her till the trans fluid makes the 0-180F range . . .
That should be easy. You don't even have to start the engine to get to that range ;)

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kassim503
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#186

Post by kassim503 » 12 years ago

http://nissandiesel.dyndns.org/viewtopic.php?t=1518

Al, you just responded like a hawk

ahahah im gonna take her out and average 4 mpg for that trip :twisted:

That could be the problem, if the soft lines are good (I know the engine side one is ok)
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

rlaggren
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#187

Post by rlaggren » 12 years ago

The kickdown switch may not be getting wet but it might be "getting mat". A lot of my cars seem to have migrating floor mats which like the high upper corner behind the accelerator - might take a look.

Rufus
82 Maxima wagon

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kassim503
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#188

Post by kassim503 » 12 years ago

While slathering some exhaust sealant on the manifold, i found that little plastic booger with 3 vacuum lines connected to it was melted from the exhaust leak. I lucked out, I didnt burn a injector, phew! Would solve the rough idle problem, unmonitored airflow, and causing ignition advance problems. I just dont know what this booger is called, anybody know?

I got names like coolant temperature vacuum control unit, but I know thats not right.

Oops, I didnt check the kickdown switch while I was working on it, ill check tonight or tommorow.
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

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asavage
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#189

Post by asavage » 12 years ago

Probably a Thermal Vacuum Valve ("TVV"). Controls vacuum flow to both the EGR valve (disabled when engine cold) and distributor vacuum advance.

Picture of in in the 1983 FSM on page EF & EC-46, and a vacuum schematic of the system on page EF & EC-6.

Does not affect the transmission.

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kassim503
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#190

Post by kassim503 » 12 years ago

Yup, thats teh one, ill try to pick one up from the FLAPS.

Yeah, the transmission woes are for another day when i get a new tvv
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

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kassim503
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#191

Post by kassim503 » 12 years ago

Ordered one of the TVV's, it seems to have another name, not sure what it was cause I forgot, and I ordered it only 3 hours ago. Ill put out a update when I pick it up- fairly pricey, 60 bucks, id figure itd be dirt cheap.

Update on the transmission, it seems to have stopped doing erratic shifting when I let go of the gas, now it just seems like its really bad cold transmission shift lag, with a tendency to like 2nd gear, but if u rev it high enough itll shift to 3rd then to 4th normally. Also I think I noticed slippage after a shift, but the lockout gears are still strong. Im gonna check the fluid level again, last time I checked it was a bit above low while the trans is cold, never know.

Im gonna wait for the TVV before any more diagnosing, I gotta take things one at a time, and I have no need for the car for the next week or 2.

[edit] and still forgot to check the kickdown switch's operation, try again 2mm
Last edited by kassim503 12 years ago, edited 1 time in total.
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

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asavage
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#192

Post by asavage » 12 years ago

Put a vacuum gauge on the line to the trans' vacuum modulator. If you seem to get consistent changes (when you move the go pedal, the vacuum seems to drop reasonably, and come back when you let up), I would probably shotgun a new vacuum modulator without further diagnosis. It's by far the cheapest part that is likely to fail and is relatively easy to change.

My thinking is that it is bent and sticking, but still moving. A sticking vacuum modulator would give all kinds of odd shifting: high/hard shifts, early/slipping low RPM, odd mid-throttle downshifts.

I had this problem in 1987 in a 1970 Coupe DeVille TH400 in Salem, Ore. . -- I won't forget this one soon! Ran me in circles for a couple of weeks. The TH400 vacuum can is pretty large, and somebody had driven over a 2x4 or something and it was bent very slightly. I didn't have a transmission pressure test gauge setup back then (I had one, but it was a quarter continent away), so I'd swapped many parts before I hit on the vacuum can.

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kassim503
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#193

Post by kassim503 » 12 years ago

im just gonna change the modulator and hose without diagnosing it, itll cost me more money to purchase a vacuum gauge than to just throw parts at it. Does it just screw on hand tight? I dont see any nuts on the photos of it. Napa lists two- NAPA My guess is one for the 3spd auto and the other for the 4spd auto.

[edit] do i really have to adjust the modulator after swapping it? Mabye i will get a vacuum gauge and test it first. The modulator is on the outside on this transmission right?
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

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asavage
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Transmission shifting woes

#194

Post by asavage » 12 years ago

These don't look like they come with the fibre sealing washer. Item 'Q' below (click on any image for larger):
Image

NAPA ATP15243, $18
Image


NAPA ATP17244, $18
Image


This is one of my 1983 diesel L4N71b transmissions up in the attic:
Image Image



Gasser version of the same trans:
Image

Both of those NAPA vacuum modulators are listed as "adjustable". That means you adjust the shift point (and the attendant shift firmness: higher = firmness) using either a small flat-edge screwdriver or allen wrench, through the vacuum hose hole. Unless the exhaust is in the way, it's not difficult. I've never tried adjusting one on a Gen1 Maxima.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

User avatar
kassim503
Posts: 1027
Joined: 14 years ago
Location: Stony Brook, NY

#195

Post by kassim503 » 12 years ago

Trans stopped giving me troubles, so im back on the exhaust manifold stud extraction. First shot is to jb weld a bolt onto the top of the stud, so I can try wrenching it off, Ben you said your studs came out easy, how easy? Like finger loosen easy? or was there a little wrenching involved. Gonna try to stick a reddy heater in the engine bay tommorow to heat it up so I can get the jb weld to stick (tried today, too cold to stick). If that dont work im gonna pull the distributor and stick a left turn drill+extractor on it. On the distribtor, I think I saw two sets of bolts, one for mounting, and the other for timing, it seems like I can remove the two lower mounting bolts and remove the distribtor without messing with the timing. Am I right on this?

On the side- whats your favorite method for patching a crack in the air intake hose? Im gonna RTV my intake hose back together for a temporary fix, I dont want to source another one or make one up right now, way too cold, hell it was cold enough for me to crack the hose while gently removing it.
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

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