 | Home > Td5 > Defender TD5 Engine Rev Issue in 3rd |
 
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| landy andy Member Since: 15 Feb 2009 Location: Ware, Herts Posts: 5969  
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Nope. New one to me.
Is your watergate turbo linkage all freely moving? |
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9th Jul 2025 8:53am |
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| rgh.key Member Since: 14 Jan 2025 Location: Stoke on Trent Posts: 20  
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Thanks for the reply, I would assume so, as the engine revs freely in every other gear, I only noticed it yesterday when joining a national speed dual carriage way, as soon as the speed hits 35mph in 3rd gear the engine wont rev any more, if you move to 4th it will rev freely and past the same revs that were causing an issue in 3rd, This is why I wondered if the ECU had a limiter for 3rd gear specifically as its odd behaviour.
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9th Jul 2025 8:57am |
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| rustandoil Member Since: 08 Sep 2012 Location: Cotswolds Posts: 854  
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That really odd! There bound to be someone on here that can help
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9th Jul 2025 9:48am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17847 
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Very odd, especially since the ECM has no way to determine which gear the vehicle is in other than to compare road speed with engine speed (and it is unlikely to do that).
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9th Jul 2025 1:27pm |
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| revd Member Since: 20 Apr 2024 Location: England Posts: 269
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It's not half in/half out of low range?
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9th Jul 2025 1:40pm |
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| Mr.Jimbo Member Since: 20 Jun 2024 Location: Rugby UK Posts: 13 
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I'd check under the gear gaiter to check there is no wiring (for example the reverse light or High/low range switch) being trapped/moved specifically when the lever is in 3rd gear.
I was going to suggest if it was overboosting and 3rd was the first gear to hold boost for long enough for the ECU to derate but if it works fine in 4th/5th then that sort of rules that out. Strange issue for sure! |
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9th Jul 2025 2:04pm |
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| rgh.key Member Since: 14 Jan 2025 Location: Stoke on Trent Posts: 20
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Thanks for the responses, I will check the High/Low range although I would of expected it to do the same things in every gear with that, this is what is puzzling me, no other issues with the engine, no rough idle or anything like that unless its an issue with 3rd gear itself.. I will give it another drive this afternoon to see if the issue persists today or if its just when its cold.
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9th Jul 2025 2:08pm |
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| rustandoil Member Since: 08 Sep 2012 Location: Cotswolds Posts: 854
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Could it be the gearbox stiff in 3rd?....what about changing down to third at 40+mph and freewheeling in neutral ?
If the box is tight it would slow the vehicle.....cant see it to be honest but might be worth a try? |
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9th Jul 2025 3:03pm |
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| rgh.key Member Since: 14 Jan 2025 Location: Stoke on Trent Posts: 20
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Okay, so I have some more information on this, I have taken it out onto a dual carriage way where I can rev is out without speeding, that would be a first a speeding ticket in a defender!
Anyway I can confirm its not isolated to 3rd gear I managed to get it to do it on 4th to at a much higher speed. Symptoms, engine revs out, high pitch turbo whistle can be heard followed by a power loss which results in the car jerking. I am wondering if it a problem with the turbo dump valve not opening at over pressure, I am unsure as to how this works but there is an actuator (pictured below) which is connected to a vacuum pump thats piped into the turbo infeed pipe form the intercooler.  Click image to enlarge Can someone confirm what this is for. |
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9th Jul 2025 3:20pm |
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| Penfold_6290 Member Since: 22 Sep 2021 Location: Dorset Posts: 378 
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What you see there is the rod that operates the wastegate, essentially a valve that opens to leak off over boost so you don't do damage. The rod is connected to a valve, which has a pipe that is attached to the intercooler, i.e. boosted air. When the pressure rises in the inlet system, the valve pushes the rod and opens the wastegate...the fun part is the wastegates seize up and won't allow the turbo to leak off the boost.
So your ECM detects over pressure in the inlet manifold and cuts the fuel. They are quite easy to free off, it'll be seized on the turbo end of the rod, so a bit of brut force will free it off and then a squirt of your favourite penetrant to stop it happening again. Last edited by Penfold_6290 on 9th Jul 2025 4:54pm. Edited 3 times in total |
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9th Jul 2025 4:41pm |
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| Penfold_6290 Member Since: 22 Sep 2021 Location: Dorset Posts: 378
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A bit like this -
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9th Jul 2025 4:47pm |
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| rgh.key Member Since: 14 Jan 2025 Location: Stoke on Trent Posts: 20
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Thanks everyone, I’ll give this a try tomorrow
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9th Jul 2025 8:22pm |
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| MadTom Member Since: 10 Sep 2013 Location: Olomouc Posts: 671  
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Best check wit Nanocom, if there is some fault storen in engine ECU, if not, look on love data (with assistance) in running car (under full power) - lookmfor turbo pressure values.
To check the waste gate, disconnect it for the controll rod and try to move only the lever on turbo - it should move freely. Also check air hoses after turbo and in fron and after intercooler. Sometimes the internall layer delaminates, resulting in and "bubble or flap" inside, preventing airflow from turbo to engine intake. Hoses should be "hard" not like very soft rubber (buvle gum), when you touch them. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo |
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10th Jul 2025 7:06pm |
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| rgh.key Member Since: 14 Jan 2025 Location: Stoke on Trent Posts: 20
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Can confirm that the waste gate was indeed jammed! Lubricated it up and loosened if off until it was nice and free, put a little high temp grease around it to try and help it from seizing again, however, now I know about it I will check every so often
Thanks for all your help! |
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12th Jul 2025 11:21am |
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