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Transmission "Roaring" Sound - Questions about Cause/Fix

4K views 24 replies 10 participants last post by  RRPhil 
#1 ·
First time post. My 2008 Range Rover HSE currently has 125k miles and has started to “roar” slightly when I accelerate (i.e., RPMs go up but torque and acceleration is delayed). It is drivable and not terrible right now but could be getting worse. I am not mechanically inclined but assume it might be the transmission. I’ve owned the vehicle since new and records from my independent mechanic (now out of business) shows a “transmission service” for what looks like 4 Quarts ($44) and labor ($38) that he did with the scheduled 105k mile maintenance service 4 years ago. Customer complaint was “transmission periodically slipping.” I’ve read many of the transmission fluid drain and filter change posts on this forum which are very helpful. I realize transmission fluid/filter change is preventative maintenance and not generally a repair. But my question is whether the “roaring” sounds like a transmission issue that might be helped with the fluid/filter change? I could do that myself. Based on my records/memory, I assume the fluid was just drained and refiled 4 years/20k miles ago. Maybe the filter needs to be changed anyhow or maybe I just need to check to see if the fluid is low? But didn’t want to incur that cost/labor if I was going to have to find someone inspect or do a major transmission repair anyhow. My iCarsoft Tool (CRPro) shows no faults. Any thoughts would be very appreciated about potential cause, and my next best move?
 
#2 ·
First time post. My 2008 Range Rover HSE currently has 125k miles and has started to “roar” slightly when I accelerate (i.e., RPMs go up but torque and acceleration is delayed). It is drivable and not terrible right now but could be getting worse. I am not mechanically inclined but assume it might be the transmission. I’ve owned the vehicle since new and records from my independent mechanic (now out of business) shows a “transmission service” for what looks like 4 Quarts ($44) and labor ($38) that he did with the scheduled 105k mile maintenance service 4 years ago. Customer complaint was “transmission periodically slipping.” I’ve read many of the transmission fluid drain and filter change posts on this forum which are very helpful. I realize transmission fluid/filter change is preventative maintenance and not generally a repair. But my question is whether the “roaring” sounds like a transmission issue that might be helped with the fluid/filter change? I could do that myself. Based on my records/memory, I assume the fluid was just drained and refiled 4 years/20k miles ago. Maybe the filter needs to be changed anyhow or maybe I just need to check to see if the fluid is low? But didn’t want to incur that cost/labor if I was going to have to find someone inspect or do a major transmission repair anyhow. My iCarsoft Tool (CRPro) shows no faults. Any thoughts would be very appreciated about potential cause, and my next best move?
Torque converter. If you’re not ready to fix it yourself, or spend a few grand sorting the transmission… Sell it or trade it. NOW.

Could be seals in the mechatronic preventing enough pressure from building to fully actuate the solenoids.


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#4 ·
Torque converter. If you’re not ready to fix it yourself, or spend a few grand sorting the transmission… Sell it or trade it. NOW.

Could be seals in the mechatronic preventing enough pressure from building to fully actuate the solenoids.


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Thanks for the reply. The vehicle has become a second vehicle that doesn’t leave town. I plan to keep it around unless things get too bad, and paying a few grand is cheaper than the alternative. If it turns into more than that, might decide to get rid of it. Figured my idea of just changing/topping off the transmission fluid myself was wishful thinking.
 
#3 ·
Bert, periodically I get a high rpm roaring from the transmission after I have previously driven it on a hot day. It usually lasts a short bit but I always take it easy on it while it's acting like this. I don't know what it is but I've experienced the same thing in other vehicles as well. Definitely heat related but don't know how. Is this what you are experiencing?
 
#5 ·
My issue does not seem to be heat related. The high RPM roaring occurs at when I driving after first starting the car and after I’ve been driving awhile, and regardless of weather temp. But the problem is kind of intermittent or I guess more related to how fast I am accelerating. Was hoping I could a fluid change might let me keep the car going without too much expense. It doesn’t leave town so I’ll limp it along until I find someone can look at it.
 
#6 ·
Bert - You say the RPMs go up but the torque and acceleration are delayed. Need a better description. Does this happen from a standstill, ie. 1st gear where the rpms go up but it doesn't feel like it's linked to the transmission until it starts to grab? Or does it feel like it grabs immediately but then the motor breaks free of the transmission and the rpms runaway from the transmission until it grabs again? Does this happen in any other gears or group of gears?
 
#7 ·
The higher-than-normal RPMs happen primarily when going from 1st to 2nd gear primarily, but it does occur in the later gears when accelerating. It feels like the engine is linked to the transmission the whole time and the shift from 1st to 2nd gear (and all other gears) is smooth. So I don’t totally lose acceleration. But I may not have the ear/knowledge to figure out what the transmission is really doing. I just ease of the acceleration to keep the RPMs back in normal range, and the car is driveable for my short drives in town. Doesn’t seems like the vehicle is slipping out of gear. I just tried to replicate the issues and could not get the high RPMs now. I do have a hard time finding mechanics in my area that can/wants to work on a Range Rover so any input is appreciated.
 
#8 ·
Engine feels like it's linked to the transmission the entire time and the shift from 1st to 2nd is smooth along with all other gears... I guess I'm not following, what's the problem again?

Regarding indy shops not wanting to work on the rangie... Tell them it's a Ford F150 (Explorer, Expedition...) transmission. Ford dealerships are more than equipped to deal with them but they pretty much have the same mentality as all other mechanics when it comes to transmissions to just replace them. Shops usually don't like going into them.
 
#9 ·
I think you need a more scientific approach. Is your iCarsoft diagnostic kit capable of recording live data?

If you plot engine speed, turbine speed and output speed it will tell you immediately whether the transmission or torque converter are slipping inappropriately. You can also monitor fluid and coolant temperature and check that clutch pressure demand is proportional to engine torque.

These are examples of results from other forum members using the GAP Diagnostic IIDTool to measure and record data (with a capture rate around 3Hz) to analyse torque converter lock-up clutch performance and check for clutch slip.







Phil
 
#10 ·
That software and data does seem like the type of diagnostic tool I need to run. I can get some real time data including from iCarsoft and it does do some charting but don’t think to the level you posted. And if it does that’s probably beyond my capabilities. I go from thinking “my transmission/torque converter” is about to "go out" to the car running seemingly fine. I’ve been driving around trying to replicate the issue and basically at around 2nd and 3rd gear with light or acceleration (25-30mph), the RPM gauge goes from 1500 to 3500 for no particular reason. In sum, speed stays the same, but RPMs go up by 2000 RPMs. Wish I had better data. May have identified someone locally with a Land Rover diagnostic computer that can sort it out. Guess it’s time to put some money in the transmission at 125k miles. And hope to avoid the let's just replace everything approach.
 
#12 ·
Thought I'd mention this since you say you're not mechanically inclined. Had a similar issue on my LR3 and it turned out to be an open thermostat due to a cracked coolant line. The roar/woosh sound was the engine fan. It is worth checking your coolant levels. The leak was on top of my engine and coolant pooled until it boiled off. There was no visible leak and it wasn't enough to raise the temps even during the 100+ F summer days in TX.
 
#13 ·
Thought I'd mention this since you say you're not mechanically inclined. Had a similar issue on my LR3 and it turned out to be an open thermostat due to a cracked coolant line. The roar/woosh sound was the engine fan. It is worth checking your coolant levels. The leak was on top of my engine and coolant pooled until it boiled off. There was no visible leak and it wasn't enough to raise the temps even during the 100+ F summer days in TX.
Exact same type of thing happened to me on my 2012 L322. There is a PLASTIC Y-pipe under the supercharger which cracked and was leaking coolant. No drips, just phantom disappearing act. Had to top up 1-2 quarts of coolant weekly.


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#16 ·
My thought immediately turned to the prior fluid drain and fill. $44 for 4 quarts of transmission fluid? That's 11 dollars a quart from a shop, so he got it much cheaper than that. That is DEFINITELY not ZF fluid that was put in there, and more than likely some really cheap stuff. The first thing I would do is have it flushed and filled with ZF fluid which should always be used for this ZF transmission and then see what happens. Refer to the manual for the exact procedure to do that, and if you're not comfortable with it, take it to a RR specialist.
 
#20 ·
I can’t see any reason why GAP would use any solenoid numbering system other than ZF’s so, yes, Pressure Control Solenoid 6 Driver should be the correct one. This is the proportional solenoid for the torque converter lock-up clutch and should yield values between 0.048 (i.e. 48mA) and 0.848 (848mA). To be honest, if it doesn’t slow down the capture frequency, it would be better to measure the current for all of the solenoids in case one of the clutches is being dropped, causing the engine flare.



Phil
 
#21 ·
Okay, I will go in and check it all out again and see what I can find. As a point, and I have no idea if it impacts things or not, but that picture is not representative of my mechatronic. I have a 6HP28 so my solenoids are: (2) orange, (2) blue, and (3) yellow. It could totally be the same, just different colors, or completely change things, just want to make sure I give that information too since you're the expert!
 
#22 ·
Sorry, I got confused as I thought we were still discussing the OP’s “roaring” issue on his 2008. I hadn’t twigged that yours was a different issue and on a 2010.

There’s very little information out there on the 6HP28 hydraulic circuit but the Gen. 1 & Gen. 2 solenoids are in the same positions on the Mechatronic unit and act upon the same circuit i.e.

EDS1 = A Clutch (6HP26=Yellow, 6HP28=Orange)
EDS2 = B Clutch (6HP26=Blue, 6HP28=Orange)
EDS3 = C Brake (6HP26=Yellow, 6HP28=Blue)
EDS4 = D Brake & E Clutch (6HP26=Blue, 6HP28=Yellow)
EDS5 = Main Pressure Control (6HP26=Blue, 6HP28=Yellow)
EDS6 = Torque Converter LUC (6HP26=Yellow, 6HP28=Yellow)

I think that MV1 (6HP26=Black, 6HP28=Blue) may be referred to as EDS7 on the Gen. 2 transmission as it’s a proportional pressure solenoid and not just an on-off one.

Phil
 
#23 ·
Yeah sorry for the confusion. I just saw you post those logs/graphs and I wanted to get the values to log so I can start a new post. I'll stop derailing this one now!

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#24 ·
It sounds like the same thing that happened to my 04, at about the same mileage. The transmission would slip occasionally, especially when it was hot. The engine rpm went high with little power going to the wheels. It got progressively worse within a month or two, till it would go into limp home mode. I looked for many different explanations on-line, but when my mechanic dropped the pan of the transmission he knew immediately from the smell that the clutch packs were burnt, and I needed a new transmission.

I talked with the local ZF rep, he said it is very common for them to fail like this at 125K, if proper maintenance was not performed. He recommended replacing the fluid and filter every 60K miles, definitely no more than 75K, otherwise the transmission will need to be rebuilt/replaced.

The 104K service was too little, too late. Only 4 quarts replaced, sound like he sucked as much fluid as he could out of the fill hole. A usual service is 7 quarts. It takes 10 quarts when filling from dry.
 
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