240sx Project, need advice

[bsilva20]

Hi. So I am a new 1991 240sx owner with a ka24de, and I have a few problems I need advice on from some real gear junkies.

First off, my transmission. It is an automatic, and the problem I have is that it downshifts everytime I let off the gas in overdrive. The overdrive button doesnt stay on itself, so I put tape around it the day I got the car, and sometimes it runs fine, other times it drops out of gear like I described. What is my problem? Mechanical or electrical/computer.

Also, when I am accelerating, a loud screeching noise comes from the engine. I was told that it is my "tensioner" I am wondering is it my tensioner pulley or timing chain tensioner under the valve cover. It screeches loud at about 3200 rpm, then stops when the transmission downshifts. What is likely my problem, and what should I replace, or can it be fixed by tightening, loosening.

Finally, my car is throwing out smoke, and I am pretty confident the valve stem seals need replacing. What is the recommended process to replace these, i.e. tools, parts, etc.
Thanks a bunch!

[liquid_cool]

the sqeeling is most likly a belt..but dont quoat me on that as im not infront of it to really diagnose it...as for the valve stem seals..if its your first time taking on a project...then plan on a nightmare trying to get the hang of it...after a few removals and replacments..it goes a little faster...to really understand..you need to read a book "Engine Blueprinting" its a S/A brand book..its short with no fluff..just strait to the point and will give you more insite into motors than any forum can...should take all of 20 mins to read...dont get scared to take this on..yes its tough the first time...but worth learning for the next time...good luck

[2_Liter_Turbo]

Hi. So I am a new 1991 240sx owner with a ka24de, and I have a few problems I need advice on from some real gear junkies.

First off, my transmission. It is an automatic, and the problem I have is that it downshifts everytime I let off the gas in overdrive. The overdrive button doesnt stay on itself, so I put tape around it the day I got the car, and sometimes it runs fine, other times it drops out of gear like I described. What is my problem? Mechanical or electrical/computer.

Also, when I am accelerating, a loud screeching noise comes from the engine. I was told that it is my "tensioner" I am wondering is it my tensioner pulley or timing chain tensioner under the valve cover. It screeches loud at about 3200 rpm, then stops when the transmission downshifts. What is likely my problem, and what should I replace, or can it be fixed by tightening, loosening.

Finally, my car is throwing out smoke, and I am pretty confident the valve stem seals need replacing. What is the recommended process to replace these, i.e. tools, parts, etc.
Thanks a bunch!

Welcome to not only NICO, but to the world of 240s. The belts are either too loose or too tight. A good rule of thumb is to take the belt and twist it with your hand. If you can twist it past 90 degrees with ease, it's too loose. If you can't even get it to 90 degrees, it's way too tight. Every belt has a tensionor. The AC belt tensioner is at the bottom of the motor between the AC compressor (big thing on the bottom driver side of the motor), the water pump/alternator belt's tensioner is in the alternator bracket (top passenger side) and the power steering pump adjustment is on the pump's bracket (top driver side).

As for the smoke, what color is it? Is it blue, white, or black? Blue is oil, white (and sweet smelling) is coolant, and black is fuel. Once we know what color smoke is coming out, then it'll be easier to help you out there.

Finally, the best suggestion for the transmission is to just swap out to a 5 speed, lol. Auto transmissions just suck, ha ha. If you want to keep the auto, try picking up a good used one. Most people sell them for pretty cheap used, as no one wants them.

[bsilva20]

The smoke is a bluish white hue.

As for the transmission, I am more than down to swap it. What's the best way to go about that. I looked up a parts list, found for about $700. Is there a link giving me some insight into how to do a swap? what tools, lifts, etc. will I need

[sx moneypit]

The smoke is a bluish white hue.

As for the transmission, I am more than down to swap it. What's the best way to go about that. I looked up a parts list, found for about $700. Is there a link giving me some insight into how to do a swap? what tools, lifts, etc. will I need

Look at the top of this page and you will see a thread about the swap.

[bsilva20]

Got a new problem. My alternator had a bad connection, so I fixed that. The car sat for about two weeks, with maybe a 1/4 gallon of gas. I fixed the connection, put a new battery in, and turned the ignition. The car turned on, idled for a few seconds, then backfired and died. I put new gasoline in it, and now it wont start at all. Did I clog my injectors by letting it sit and then starting it and running it pretty much empty? Please let me know what I'm looking at.