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Old 10-16-2012, 07:31 AM
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O/D Light, towing questions

I just picked up a 95 OBS 7.3 PSD dually. Has 190K on it. The trans died very shortly after getting it. Got it rebuilt and took it for its first voyage with the rebuilt trans. Towing a car with a fairly heavy open trailer (maybe total of 5K pounds).

My O/D light started flashing on my way to the destination after about 4 hours of straight hwy driving (no stops at all), maybe going ~70mph the whole way. It was about 20 minutes to my destination. After getting off the highway and coming to a few full stops it shut off and never came back on.

I read various things about the O/D light, but I guess one question would be is it possible that I just was driving too long without any stops? Is there a recommended time for a stop when towing at all, like every 3 hours or something?

The trans felt normal the entire time, on the way home I drove 2 hours stopped for gas then finished the remaining time and it never came on.

I will be taking the truck back to where I rebuilt the trans, but the light has yet to come back on so not sure if they will find anything.

Its under a one year warranty as well.
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Old 10-16-2012, 10:56 PM
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You need to get the codes pulled. You wern't driving too long unless it overheated somehow.
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Old 10-17-2012, 04:13 AM

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Yeah, pull the codes.

Just out of curiosity, did the place that you got the transmission fixed/replaced at tell you what happend and what caused the transmission to go bad in the first place? Not trying to pick on them but sometimes, people will put transmissions in without fixing the issues as well. So, they can put in a new tranny but 10k miles down the road..."pop"...there goes another one.

So, did they get a remanufactured one that was tested or did they rebuild it themselves? If they did, how did they test each solenoid and the electronics for the transmission like converter lockup switch, shift solenoids, and about a dozen other fun electronic goodies?

I was no tranny expert but I had to diagnose them and A lot of times, when I got to the end of the diagnostic tree and it said to replace the transmission, I went through the tree one more time to be sure. Then, when we did replace them, "usually", we just got a Ford reman so we wouldn't have to worry about dealing with warranty issues. We were just a dealer and not a tranny shop and didn't have the necessary tools to test the transmissions after they would have been rebuilt had we rebuilt them so we "usually" didn't.

So, I would just ask them if they tested the internal electronics of the transmission and if so, how? You don't have to be a prick about it but a shop can "tell you" they did testing on something but usually a few questions here and there will uncover the truth of whether they actually did go through all the steps to PROPERLY test the transmission of if they're just feeding you full of BS and they just put new clutches and seals in and "hoped" the internal electronics were fine.

With transmissions of today (or in the OBS situations, 20 years ago almost), it's not as simple as setting the proper kickdown adjustment or vacuum or making sure the PRND2L lever lines up correctly to get it in the correct gear. You can't just slap a rebuilt trans on a trans machine and let it go. To PROPERLY test these transmissions, you need to have the capability to engage or disengage certain things within the transmission at certain times under ceratain loads like in a truck. So, you have to have the right testing equipment to do so.

So, my question is, did they have the right equipment? If so, ask them to show you. Ask them to discuss what caused the issue for the tranny to go out before. Things do wear out so maybe it simply was age and it just needed some things like seals and clutches and so on. But maybe it was something more and now that something more is coming back to haunt you.

I hope not but just ask so you know.

And good to hear they will honor the warranty. And btw, did you have them remove and install the transmission? If so, do you know 100% for sure if they cleaned the transmission lines and cooler? I know it should be a given but sometimes people don't. If you had someone else take it out and reinstall it, did they clean out the transmission lines?
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Old 10-17-2012, 05:49 AM
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Thanks for the detailed response.

They did speak with me a little about what went wrong with the transmission, but it was very foreign language to me. My knowledge of transmissions is only for small car manual transmissions (just gears). He showed me some burnt disks and a cracked piece or two.

He mentioned it was obviously overheated and did check the cooler and said it was flowing fine after they took it out.

He didn’t speak much about any electronics though.

They rebuilt the trans themselves, and did the swap themselves. Place is called Mr. Transmission if that is of any help.

I am planning on getting a temp gauge for my trans as well soon just to keep an eye on temps.

I will be headed back there in about a week or so (not planning on using the truck anytime soon) so hopefully they can figure out whats wrong.
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Old 10-17-2012, 08:47 PM

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The place doesn't matter to me because I don't care. Plus, I'm not here to call anyone out specifically. And besides, even the best can rebuild 100's of engines and trannys and have one go bad every now and then. Parts fail even with all the testing in the world done to them. So, that is not my intention of the post.

But as an example, I recently purchased (ok, it was last Thanksgiving now) a minivan with the transmission out (guy couldn't afford to have the transmission fixed so I got a steal) and after I put a different used transmission in it to get it goin again, I went to pick the original transmisson up from the guy who was going to rebuild the old one. He told me that the insides were basically shredded (which I could obviously see) and that he recommended NOT using the same shift solenoid pack of the original transmission on the new (used) one. The reason??? Since the insides were shredded with clutch disk debris and metal particles and debris, this debris could have possibly (and HIGHLY LIKELY) made its way into the shift solenoids. So, he would have rebuilt the transmission with a different solenoid pack to ensure it's longevity.

Now sure, I already knew this but it was nice to hear him say it and it told me a lot about his knowledge.

There are a lot of guys who can tear down a rearwheel drive tranny and even rebuild them by replacing all the clutches and seals in it if they have the tools to compress clutch packs and so on. HOWEVER, a lot of these guys FAIL TO REMEMBER that the internals of the transmission flow everywhere in a transmission once it starts to go. This NOT ONLY means the internals of the transmission, but also the torque converter (a lot of people do NOT change the torque converter resulting in issues), the valve body (a ton of little passageways, small balls, and nooks and crannies for metal debris and clutch particles to lodge their way into), and of course the electronic solenoids and other electronic components (although they have small holes, debris can still make their way into these components causing them not to function properly which in turn causes your tranny to function improperly).

So, just because you can tear down a tranny, clean it out really good, and put new clutches and seals in it does NOT mean that you actualy rebuilt it PROPERLY. (KEY WORD THERE.....properly).

This is why many many dealerships and private shops do NOT screw around with transmissions. There are just too many little things to go wrong with them and the cost of the PROPER EQUIPMENT to test them is costly. Compared with the amount of times they will need it over the years may not justify investing in it.

So, it's just easier to send a transmission to a transmission shop that specializes in trannys or get a remanufactured one. Either way, usually they have a warranty so they can rely on that.

Anyhow, if I were you, I would ask them if they tested each solenoid on the tranny? If they tested the torque converter lockout switch and it's operation, if they dismantled the valve body and adjusted it correctly. If they cleaned each solenoid BEFORE putting it back in the transmission? Ask how they cleaned the tranny lines and cooler.

The thing is, many shops aren't used to getting questioned because most people don't know any better. Like you mentioned, the language shops use can be "foreign" to many people and as a result, they usually just "take for granted" that the shop is doing what they're supposed to in order to fix their vehicle.

But when you start digging deeper and asking direct questions (like a few I mentioned), you start to uncover some inconsistencies. In most cases, a lot of shops can't answer these questions with honesty because a lot of shops probably didn't do some of the things mentioned. Why? Well, simply put, it takes time. And time is money to a shop. So, to get paid for their time, they would have to tack it onto your already HUGE bill. And nobody wants a larger bill than they already have right? So, instead of spending the time to take the preventative measures to ensure your future transmission's life, they just skip these things.

Again, why it's just easier to leave this stuff to a transmission shop that does it on a regular basis.

I'm not saying that your solenoids are ruined or any of your other electronic stuff inside or outside of your tranny but anything is possible.

Either way, I hope they will be willing to work with you to fix your issue.

And just so you know, even though a transmission gauge is nice, what does it change? A transmission gauge won't change how your transmission shifts or runs or anything else. It will only allow you to monitor the temp of the tranny. It won't unclog a clogged tranny line or cooler. The main thing about a gauge is that you NEED to do something about the temp if it gets too high. So........instead of constantly driving your vehicle if the temps get too high, what are you going to do? Will you pull over and wait 15-20 minutes for it to cool a while or keep driving?

My point in this is that gauges don't change anything within the vehicle itself, they only allow you to monitor them. You have to change your driving behavior if you're going to get a change out of the gauge.

If you haul a lot, I wouldn't just put a tranny cooler on (or an additional one if it's already got one on the radiator), I would mount a fan directly to the cooler OR BETTER YET, add another cooler with another fan. Heat is one of the number one causes of tranny failure so if you can minimize or eliminate that, you'll be golden. For me, I would rather invest my money on another cooler than a gauge but that's just me. If you have money, do both.
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Old 10-18-2012, 06:44 AM
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Thanks again, really really useful tips.

In terms of hauling, what do you consider to be a lot? Typically all I would be doing is about every 3-4 weeks (warm seasons) a 4 hour trip, and once or twice a year 12 hour trip. This is with about a 5K pound load.

I will probably opt for the fan for the time being, it does have a cooler already, I'll look into an additional cooler/fan setup over winter time.
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Old 10-18-2012, 07:43 PM

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Honestly, I think you should get multiple opinions on this. The thing is, it really comes back to what YOU feel comfortable with. (Not to change the subject but recently I posted about buying a 1995 F450 and some thought I was basically out of my mind and it wasn't worth even close to what they were asking and others understood that I wanted for hauling and didn't care about looks and thought it was a pretty good deal).

So, people have different thoughts on what is extreme or what is acceptable or normal.

Here's my take though:

If you're hauling a car trailer with an average car on it and the total weight is about 6,000 to 7,000 pounds (2,000 or so for trailer and 4,000 or so for car), then I would say you should be ok with this without an additional cooler IF...IF you're driving on "mostly" flat terrain with only a few large hills here and there.

But, if it's in mostly hilly or mountainous terrain like say between Denver and Las Vegas (mostly ALL mountains except for the last 50-100 miles to Vegas) then I say you need an additional cooler even hauling a small trailer or car trailer. Heck, just the pickup alone without a trailer and I would consider it. Especially if I was traveling a lot of distance in that area every day.

The reason I say this even for just a pickup is because going up and down a mountain area will cause constant downshifting and upshifting and back and forth and back and forth. Over time, it will create more friction and heat which is what we all know we want to prevent.

So, I would "consider" it even for just a pickup.

Now, if you're hauling something heavier like a large pickup on a trailer or more weight than a car trailer (8-10k plus) then I say you should probably put a cooler on). Anything above this and I say it's almost a must.

But alot of this will come back to the way you drive your vehicle. I say this with the idea that most people drive faster than they should with trailers when going through mountains because they're impatient. So, they're usually trying to gain a lot of speed going uphill and go 65 or 70 plus. Shoot, a lot of times, I hear people that want to do 75 to 80 plus. I think back to when I was a tech and I was working on a few construction company's trucks and they would tell me how they would easily drive 75 or 80 plus going uphill with their trailers loaded with a skidloader or something else. They bragged about the power the powerstrokes had compared to what they used to have. Of course that 215hp/335 tq. rating is peanuts compared to more than double in today's world but that's a different story.

Point is, they drove the crap out of them and abused them. Sure, you can drive them that way and probably even go a little faster uphill with them if you want BUT, they are meant/designed to do that. Especially not on a regular basis like construction workers.

So, if you are "nice" to your truck and drive it where you maybe only lose a little bit of speed when going uphill and just try to maintain speed like around 55-60 (65 max) AND keep it out of overdrive while driving through the mountains, then you could get away with maybe hauling a little more weight a little more frequently without an additional cooler.

But this is with you keeping your foot out of the throttle going up hill to minimize the load/pressure on your trans as you're going uphill.

Also, if you change your fluid & filter every 30,000 to 40,000, you would be able to get away with a little more than if you're doing every 60,000 to 75,000. Heck, some people don't ever change it until it's at 80,000 or 100,000 and "I don't know what happened but it started slipping" comes into the shop and they have NEVER changed fluid & filter since they bought it new.

So, to me if it's a car trailer with a car on it every other weekend or so, I say you're probably ok if you drive it ok. 70 to 80 on a flat terrain is nothing and I won't get on anyone for driving them a little faster on flat terrain. It's when you're trying to race a rice burner up a hill at 80 with your camper on the back that makes me want to bi*ch slap some people. Not to mention the safety of trying to drive so fast through mountains or high hilly areas.

I'm a fast driver so I'm not trying to be hypocritical but even I know my limits of my vehicles.

Now, as for the trans cooler, one thing to **CAUTION** you about is the placement of it and how long (or big around) the lines are. Here's the thing about adding a cooler:

The transmission has an internal pump that can only pump so much fluid through the lines and inside the tranny to circulate fluid. (UNLESS YOU HAD A TRANNY BUILT WITH A HIGHER CAPACITY PUMP but let's just keep this conversation for a regular ol' trans). As such, if you add a cooler and lines, it will take more fluid to fill that cooler as well as the lines to get it to and from the tranny. As such, you will be working the pump harder to try to push more fluid through all of this exrtra stuff. So, you want to keep it to a minimum as much as possible. Make sense?

Now, all automatic transmissions have a trans cooler somewhere on the vehicle already as standard equipment from the factory. Most have them "built into" the radiator along with the cooling system for the water pump. (you will see this when the radiator has those small aluminum lines going into the top and then one coming out of the bottom.) However, trucks may have a separate cooler from the radiator (that looks like a smaller version of the radiator) either in front of, below, or somewhere close to the front of the vehicle. Some trucks do this as a standard thing from the factory and others may offer it as a "towing package" option.

I'm not sure which one yours has but you'll have to find out. Also, there may be 2 extra small radiators/coolers OTHER THAN the big radiator on your vehicle. This is because a lot of vehicles ALSO HAVE a power steering pump/line cooler somewhere near or in front of the radiator as well.

So, don't confuse your trans cooler with the power steering cooler. Usually, the trans cooler is larger than the the power steering cooler.

So, if you already have a separate cooler on your truck as standard equipment, I would just consider putting a fan on the back of the cooler (if you have room) or in front. I personally recommend putting it on the back (with airflow from the front of the cooler in front of the vehicle through the cooler to the rear of the vehicle the fan would be on the rear where air comes through) of the cooler because when you "suck" hot air out of the cooler, it cools it quicker than if you "push" it through the front. Especially on really hot days of 100 plus when you're just pushing hot air through the fins of the cooler.

But room might not allow it.

If you put one fan on and it drops your temps from 220 or 225 (not good) to 180 or 185 (more desirable and a little lower is better) while pulling a load, I would say you're good. But, if one fan isn't enough, put one on the front.

You really shouldn't need more than 1 external trans cooler (not including the one that may be "built in" to the radiator) even for most higher load and frequent hauling situations. In extreme situations you may need an additional one but REMEMBER, your pump will just be pushing more fluid through these lines and extra cooler so you may be overdoing it for your pump.

I have heard of people mounting their additional coolers under the body of the vehicle and on one side or the other but because something from the road could damage the cooler or puncture a line AND...I don't think it would cool as well since the airflow would be a lot less than the front, I think you should try to locate a place in the front if you do it. At the very least, no matter where you do it, make sure to mount it as upright as possible since angling it will decrease cooling efficiency, and out of the way where it can be damaged.

Last, I would join in the conversation on here about trans coolers if you haven't already.

Here is the link:
trans cooler
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