Loss of power and transmission whine after warm

[Alcyone]

Hello, I recently bought a 93 Q45 with 180k on it. The thing runs really good, but there are a few minor issues.

1. The car has developed a whine after it warms up. It sounds like the transmission and is present in all gears and at all RPMs. It's similar to what one would hear on a manual car driving in reverse.

2. Also, it seems to lose power after it warms up. Before normal operating temperature, the car feels torquey and powerful, but loses that umph after being driven a while.

Since I've owned this car, I have changed the oil, cleaned the MAF and replaced the air filter. I imagine I'll do a transmission service on it too (fluid change and filter) and the fuel injectors will need to be replaced soon.

Are any of these problems something to worry about? Particularly the whine?

Thanks in advance.

[qship96]

sure it isnt the differential? if transmission is whining check fluid level & color,and prepare for possible replacement

[Q45tech]

180k is pretty good life for an AT in 90-93 series............most diffs last that long also [assumming decent fluid change intervals [every 30k].

Take it to dealer for a full paid inspection and a total list of needed repairs/replacements. Then decide who will fix what later.....after consultation with forum members.

[Alcyone]

I checked the transmission fluid level and it appears to be full. Also, the color looks OK - still clear with no burnt smell. I'll check the diff level and post back.

[maxnix]

Also, the color looks OK - still clear with no burnt smell. I'll check the diff level and post back.

"Clear", not bright pink via the white paper towel test? Wonder which ATF that is?

First thing any new Q45 owner does is replace all the fluids unless written service documentation indicate one or more was replaced with correct fluid within desired service intervals.

Presume you have read the timing chain guide article? If not, please do so before you ever start your car again.

[Ozzie]

Didn't the '93 get the metal backed guides??

[Alcyone]

The fluid is pink, but I can see through it.

I have read that article. The engine was replaced recently so I assume the metal backing was used with the timing belt.

I'll probably have transmission flushed with a filter replacement and the transfer case and diff fluids replaced. I was thinking of aamco. I called another place and they told me the transmission on these cars requires synthetic. Is this true?

[bullittandy]

They don't require synthetic although many people use it. I don't think that it (syn) would be a good investment on a 180K transmission though.

Loss of power could be knock sensors.

[Q45tech]

As far as I can tell all ATF made [dextron types ] is all SYNTHETIC as the base oil is hydrogenated [semisynthetic].

Synthetic can be hydrogenated or PAG/PAO single molecular sized based oil.

The transmission uses a ATF temp sensor to control the shift pressure and limit overdrive AND lockup clutch action until the ATF is warmed to standard.There are no pressure sensors so this temperature vs pressure curve was recorded on brand new transmissions and just put in software [memory].

As a transmission wears these pressures drop from internal leaks around seals and the transmission pump itself may be worn lowering the maximum pressure.

Very common problem is a blocked or partially clogged in radiator heat exchange which STARVES the rear planetary gears of lubrication which shows up as a whine.

Obviously a noisey diff is less expensive [used $300-$500 + 3 hours] than a remanned transmission [$3,000] or a used junkyard iffy unit [which may be worse from sitting after abuse for $500 + $400-$500 labor].

We had one customer who brought his own junkyard units, it took 3 Paid swaps to find one that functioned [it worked but was noisy and failed again in 7 months] finally he bit the bullet and went oem remanned.

Luck of the draw is not always good.

[Q45tech]

We probably should redefine the way we speak of ATF to NISSAN OEM, GENERIC- Dexron, and PREMIUM PRICED [Mobil 1 Syn, Redline, others].

[qship96]

We probably should redefine the way we speak of ATF to NISSAN OEM, GENERIC- Dexron, and PREMIUM PRICED [Mobil 1 Syn, Redline, others].

using your 3 above catagories,which is the best fluid,and would you use different service intervals for the different catagories?

[Jesda]

Didn't the '93 get the metal backed guides??

Not officially.

[Q45tech]

If the transmission had an add on external filter and extra cooling one might find it cost effective to run a premium ATF................and extend the flush intervals...............depending upon the time it takes for the dye to change color [desaturate].

I sure wouldn't waste money on premiums until the interior was varnish free and clean as new.

[maxnix]

Not officially.

Means only 1 or 2 known 1993 G50 have had the metal backed guides on NICO or its predecessor boards. I think it is only one, and it was not established beyond a doubt if it came that way from the factory.

Hence, if you have a 1990-1993, you must remove the timing chain covers and look, unless you have written documentation to the opposite. Beware that usually only the slack side guide was replaced in many of these instances, so still worth looking. Who knows if all the pieces were recovered from the oil sump?
Modified by maxnix at 11:51 AM 11/9/2006

[Alcyone]

Now that I think about it, I don't think it's the transmission. I read somewhere that it could be the belt pulleys. What does a transmission whine sound like?