Hi all. I am new to this forum and the Volvo world. I recently bought a 1992 740, non turbo Wagon. I am the second owner. The car has 248,000 miles on it.
I am experiencing a Rough Idle issue(cold start only) when first started up after its been sitting for more than a few hours. The engine "lobes" for about 1 minute exactly and then will smooth out. I can put it into gear and it will smooth out sooner also. The tach though will still jump slightly after the minute period in park. A new throttle body was installed recently. The spark plugs are burning good. There seems to be a valve slap or some other noise in the number 3 cylinder also. The car otherwise runs good and strong and gets good MPG. The car has been maintained very well since new by a Volvo tech, and the timing belt has been changed every 50,000 miles religiously since new. Prior to me owning the car it had sat un-driven and used only a few months a year. If anyone can help me solve this issue please message me back. Thanks

 

You could possibly have an issue with the cold start injector. It should be located around the number 2 or 3 intake valve on the underside of the intake manifold (could explain the location of the noise).

 

Hi thanks for the information. Do you know if this cold start injector is visible from the outside of the engine? What does it look like? Does it attach to the intake manifold? Is it easily to replace? If it is noisy does that mean that it is bad? Thanks for all of your help.

 

It is visible from the outside, but you may have to get down in there to see it. It attaches directly to the intake manifold underneath your regular intake valves. It isn't the easiest thing to get your hands to, but it's only held in by two screws. You have to be cautious because when testing it you will have fuel vapors present. Make sure you disconnect the electrical wires running to that injector, but not the fuel line, and disable the ignition system. I'm not sure about the noise, but it is possible if the injector is faulty. I'm just going off the fact that it's rough when cold starting and the location of the noise. You're looking to see that the injector is spraying correctly and not leaking. To see what it looks like just google "volvo 740 Cold Start injector" and look at images from auto parts stores. That's easier than me explaining.

But, it is possible that absolutely nothing is wrong. We may just be over thinking it. If your car is running fine and there doesn't seem to be any damage happening, that could be the case. Remember that at cold start the engine is going to run higher to get itself up to operating temperatures. And the noise could also just be the fact that your piston is loose fitting in the cylinder until it gets warmer and expands to a tighter fit. These old engines are going to sound like they run rougher, especially if you're new to the car.

 

Thanks for all the good information. I appreciate it. I was also wondering if you happened to know anything about the transmissions used in these Volvos. I understand that it is a AW70L tranny. I have developed a small leak in the transmission oil pan. I have decided to change out the pan, gasket, screen,(I think), and the fluid. I am not sure of the correct fluid that it calls for. The book says Dexron two D. I am not sure if that is still available and where to get it or if there is a now-a-days replacement. Also wondering about flushing the system as long as I am there. I am not sure on the procedure for doing this. Can you help me on this? Thanks for all the help. Larry

 

I bought Dextron II D at advanced auto parts the last time I did a transmission oil drain. There are a couple different ways to do a trans flush. Since you are already under the vehicle and changing the pan and gasket and all, the simplest way is to remove the trans oil cooler return line from the back of the transmission. It's a pretty simple process, basically oil is circulating from the trans to the radiator and returning via this return line. You will need an assistant. Fill to the correct oil level, turn on the car and make sure you have a pan under the return line. As oil is pumping out of this line you need to make sure someone is quickly replacing it with new oil (I would have 8 or 9 quarts of new oil unscrewed and sitting close by for your helper), while you are watching what's coming out of the return line. When the oil pumping from the return line turns from dark/black to a copper or reddish color then turn off the vehicle. You have all new trans oil. Attach the return line. Check oil level and top up. Start the volvo while holding the brake and switch to each gear for twenty seconds. Now check the oil level again. The whole process usually takes less than an hour. Just make sure you're all set up and make sure the assistant keeps oil coming in while it's pumping out. Good luck to ya!

 

Again thanks for the detailed information. I have heard from a few good sources that a drain and fill is the way to go, because there is a possibility that changing out all the fluid sometimes can cause the tranny to "give up". Conversely I have also read and heard that this method is the only way to go about it. Your procedure seems to be pretty straight forward and the way that I would go if I decide to do a complete flush. Wondering how low ago that it was that you were able to purchase Dexron 2. I am probably going to pick up fluid within the next few days and I will purchase Dexron 3 if 2 is not available. Thanks Larry

 

Hey Larry sorry for the late reply. The transmissions that give up from a fluid replacement are usually ones that have never had a fluid drain or replacement. If your car has been well maintained and had the fluid replaced regularly then this isn't something you should even have to think/worry about. The problem comes from oil that is really old and sludgy with a lot of built up grime and particles floating around in it. People worry that if you drain out the oil then those suspended particles move and settle into new places in the transmission and lock it up. If this is a concern of yours, then you might want to take it to a volvo mechanic and have them do the procedure or give you an opinion. It may also benefit you to flush the transmission repeatedly, keeping new fluid flowing out of the return line for longer than expected. This can get expensive with the cost of trans oil and amount needed, but may aid in flushing out more of the grime.

As far as getting my trans oil, I did a trans flush back in May of this year and picked up a dexron II/III synthetic oil at advanced auto. It was advanced auto brand in the black bottle. If you're having trouble finding it, I would just look on these forums for suggestions on what others are using. I know some people are using a castrol brand they are finding at wal-mart which is supposedly very reasonably priced. May be up your alley if you need/want to do an extened flush on the trans.

Good luck to ya, and keep me posted.