My Path

The Gas and Diesel Engines - VQ40De, VK56DE, YD25DDTi, V9X, Transmission, Transfer Case, Oil, Differentials, Axles, Exhaust...

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JP4
Posts: 6
Joined: Tue Apr 10, 2018 4:20 am

My Path

Postby JP4 » Sun Apr 15, 2018 7:05 am

It's an 08 bought from dealer in 09 with 43000 on it. It now has 176000. I have never really done anything to it. Tires, brakes and oil changes which I've taken on myself ever since a bad experience at one of the oil change places. Put new cabin filters in and that's about it.

I'm not here to blow my own horn. I'm starting to be more concerned due to its age and mileage. Knock on wood I haven't had any radiator transmission problems and do not know if any repairs were made before I got it.

I have never had a tune up performed on it either. It's my daily driver and I don't mind driving it daily.

What would any of you recommend I do at this point?

I would like to add that I know the fuel pump in the tank is going South. The gauge has all the normal misreading problems

And

Either u joints or possibly the wheel speed ABS sensors [the ones that bolt to the differential] are going south as well. At least that's what I suspect from the grinding rumble strip sound that happens when the car gets to around 40mph. I either let off or give it a little more gas to make it stop.

So I'm praying I'm not jinxing myself by talking about it.

Any tips would be appreciated, thanks


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smj999smj
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Postby smj999smj » Sun Apr 15, 2018 12:16 pm

Well, it's hard to recommend anything to fix the rumble sound without a little more diagnosis, but it would be a good idea to check the U-joints and tires. Plugs were due at 105,000 miles, so it would be a good idea to replace them; stick with the original type NGK's. The fuel gauge malfunction is an indication of the fuel sending unit, not the pump, itself, but I could see where one would replace the whole fuel pump module with that many miles on it. If the radiator is original, I would replace it as preventative maintenance to avoid the possibility of the trans cooler failure and, beside, you're overdue for a coolant service, anyway, if that's original. I would do a drain and fill of the auto trans fluid; I use Valvoline Maxlife Full-synthetic ATF in my two R51's which I get from Walmart for $18/gallon jug. If it's four wheel drive, I'd also drain and fill the transfer case fluid. Some might also recommend drain and fill of the diff fluids, as well. Check your struts and shocks for signs of leaks or inadequate dampening.

JP4
Posts: 6
Joined: Tue Apr 10, 2018 4:20 am

Postby JP4 » Mon Apr 16, 2018 3:17 am

Thank you smj for the information!. There are a few things I need to address then. would really like to start with the plugs but want to get rid of that vibration too.

May I ask if you know what exactly the sensors are on the differential and if they could be sending information that could be causing the vibration.

If that makes sense? If I'm way off base please let me know.

Thanks

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smj999smj
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Postby smj999smj » Mon Apr 16, 2018 4:57 pm

There only sensors on the rear diff are the speed sensors for the ABS system. It's two sensors (rear left and rear right) that converge to a single plug and is sold as one part. Unless the ABS/SLIP warning lights have been coming on or there are stored codes, I'd be doubtful as to this being the problem for your vibration. I suppose if you wanted to, you could clean the ends of the sensors, but I would first check the U-joints on both drive shafts. Keep in mind that even when you are not in 4-wheel drive, the front driveshaft still turns.

JP4
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Joined: Tue Apr 10, 2018 4:20 am

Postby JP4 » Mon Apr 16, 2018 5:42 pm

Thank you for that information it's good to know. I will check. The U's and and report what I find.

Thanks again

BCGeo
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Joined: Wed Apr 18, 2018 11:26 am

Postby BCGeo » Wed Apr 18, 2018 11:59 am

Hi JP4,

First time posting but I’ve been lurking for the last few months. Note that this is all based on the information I’ve uncovered between reading the manuals, this forum, the dealership mechanics, and a transmission shop. If anyone can correct my interpretation please do so!

The rumble strip feeling at 40MPH you described is exactly what I just went through. My pathy is currently getting an tranny rebuild since I didn’t ID this in time so hopefully you can get it properly checked before you end up like me. I’ve written out my story below, but I recommend you do a quick check to test if you’re issue is the same as mine.

CHECK:
Find a local road where you experience the rumble at 40MPH with rpms ~1100. Generally, this will happen on a road with a slight incline as the added load is enough to cause slip but not enough to downshift to 4th. You want the truck to stay in 5th gear with about 1/8 of the gas pedal pressed. Once the rumble is occurring, shift into 4th gear while remaining at 40. If the rumble stops then it suggests the issue is in the tranny or downstream (vs engine). In addition, you drive the road again but this time when you feel the rumble press the brake pedal 1/8th or less (enough to have the sensor engage but not to slow down substantially). If the rumble stops this suggests that the issue is the lock up (lock up disengages if the brake is pressed). If both these are correct then go to a good tranny shop and drop the pan. Look for evidence of SMOD and probably look into replacing the torque converter. It’s costly due to labor, but better than rebuilding the whole thing.

—-
My Backstory:
My pathy had original rad until I bought it at 91k miles. There were no visible signs of rad leaking and no past SMOD, but when I bought it I immediately replaced with in aftermarket. Based on this I went through diagnosis assuming that I had avoided SMOD.

Within several weeks I noticed the rumble when going ~40MPH with RPM ~1100 (ie when in 5th). This led to several visits to the mechanics discussing options, but it was assumed that I could drive the pathy without issue for the time being and even trailer up to 50% rated weight. I put another 2000 miles on it without any noticeable changes, but would use manual mode / OD off to keep the tranny in 4th until above 45MPH. I am moving from east to the west coast for work so started my drive, so hooked up a 2500 lbs trailer and took off. Within a day I had fully blown the tranny and had to spend a week in a town waiting for a rebulild.

The result:
Turns out that there was a tiny bit of rad leak into the tranny. What we suspect happened is that this caused early wear on the torque converter and lock up clutch material. 39 MPH in 5th gear is when the lock up in the torque converter engages. As you speed up, line pressure in the tranny increases and helps to push the clutch harder. Since my clutch material was weak from the rad fluid I was getting lock up slip between 39 MPH (lock up engages) and about 45MPH (where line pressure appears to have been enough to get the clutch to grip). This slip was registered on the TC SLIP SPEED sensor which would tell the tranny to disengage lock up and try again. This repeats, causing the rumble. Were still not sure what caused the immediate failure since the 2k miles I put on did nothing and I was doing the same manual shifting to avoid the rumble, but it is clear that my torque converter ended up failing, causing increased slip, burning the other clutches, and forcing a full rebuild.

JP4
Posts: 6
Joined: Tue Apr 10, 2018 4:20 am

Postby JP4 » Mon Apr 23, 2018 6:28 am

Hi BCGeo, thanks for the reply and information.... interesting what your Pathy did and how you responded to it. I didn't think about the tourqe converter. The list of suspect parts is just getting longer.

The rumble seems more pronounced now. I need to do something soon. I wouldn't mind keeping the truck it's been a good vehicle overall through the years.

Didn't have a chance to investigate any parts last weekend and now we're in the middle of a 3 day rainstorm. Hopefully I can look around in a couple days.

Sorry to hear about your breakdown on the trip out west. Hopefully it got fixed and you're where you're supposed to be now. I did the West to east drive when I moved out here. It was enjoyable. Had a Chevy van at the time and acquired the Pathy a few years later over here.

JP4
Posts: 6
Joined: Tue Apr 10, 2018 4:20 am

Postby JP4 » Sun May 06, 2018 6:46 am

Well as suspected the noise is from the tourqe converter. Rarely if ever is something an easy fix. That's just my experience anyway.

I drained the fluid and changed the filter. The fluid looked like mud. Not thick but brown and milky looking. Definitely bad news. We by passed the trans inter cooler lines and refilled.

Shudder is still there but not nearly as noticeable as before. I'm thinking of doing another drain and fill to see if I can get it back to a better condition.

Changed engine oil too. The trucks engine sounds good and runs fine otherwise. All new brakes were put on a couple months ago [rotors n pads]

Would like to do the tune up plugs n coils and get that sending unit replaced for the fuel gauge


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