Hi folks,

Hopefully someone can help me here. I have an '05 Land Rover LR3 (Disco 3) with Jaguar V8. I am being told the oil anti-drainback valve is leaking, causing a rattling sound to occur on startup for a couple of seconds. I thought it was the infamous secondary tensioners, but the dealer says these tensioners are fed oil through this anti-return oil valve. So, the oil leaks out of the tensioners, causing slack chains until oil pressure is restored a couple of seconds after the engine starts. I am told it is a 12-hr job to change this valve, which costs about $200US for the part.

Could somebody please post a picture of this part? A drawing of where it is in the engine? Anybody actually changed it? I guess the timing covers and the oil pan must come off.

I am looking for as much info on this as possible. I am disappointed this integral part failed after only 3 years and 50k miles. Warranty will not cover it.

Thanks

 

hmmm, this would be news to me since an anti drain back valve is part of better quality oil filters so the oil in the filter doesnt drain out and require the pump to refill every time you restart after sitting for awhile. unless maybe theyre talking about the oil diverter valve for external oil cooler, but this is accessed by dropping the pan and oil pump. That engine is fitted with the later style metal bodied upper tensioners, other wise the VVT's also can rattle on startup. How bad is it really? I dont know that I would even worry about it unless its reallynoisy or gets worse with time

 

The noise is a problem, you would not want your fancy vehicle making what sounds like a loud metallic rapping every time it starts, would you? It also will cause premature wear to the short chains and tensioners.

This is not the anti-drainback valve in the oil filter. This is a separate, integral valve behind the timing cover somewhere which acts as a 1-way valve. With oil pressure (engine on), oil pushes through the valve and 'energizes' the tensioners. With the engine off, the valve instantly shuts (maybe by light spring pressure) to keep the tensioners filled with oil. My problem is that the spring must be weak, because oil is leaking past the valve, or so I have been told by the dealer.

Still looking for info...

Thanks

 

well since Im a little slow at work( Jaguar master tech for 11yrs, and ASE master with L1) I thought I would help you. But unless theyre wrong or you mistook what they said theres no antidrain back valve to the tensioners in the oil system, and I just looked in Jaguar V8 tech guide on the the V8, the tensioners hold their own tension, and the VVT's are supposed too, but is the most common problem for startup noise on the newer v8 now. And yes you must take off the front cover and chains to change.

 

Hi Brutal,

I appreciate you looking. Is it possible the Land Rover modifications to the V8 incorporated this valve in their 4.4L version? I was told by local LR dealer this valve 'ran' the tensioners.

Are you saying there is a common problem with the VVT system? I can see the (secondary chain) tensioners should hold themselves by spring pressure, but they are hydraulic. I know nothing about the VVT cam-phasing system.

Thanks very much

 

well I try not to open my mouth about something im unsure of(still do sometimes) so not only did I look, I went and asked a Land Rover master too since we service both, and after he got rid of the same puzzled look I had thats the same thing he said, VVT's, they have internal valving and oil driven as well

 

Thanks for checking. Basically, when the car has sat for say 10 minutes or more, it makes a quick clatter for 1-2 seconds; then it runs smoothly. If it has been off overnight, the clatter is more pronounced but still for the same duration. Other than that, the car runs fine. If these oil-fed VVT's are causing this clatter, what is causing the oil starvation? Something in the VVT device itself? If that is the case, any idea how much the cost of replacement is? How long of a job for a dealer? Is it DIY for a skilled home mechanic? What has to come apart? Do both VVT's have to be changed?

Thanks again

 

IT TAKES A WHOLE DAY AT LEAST, AND HOW SKILLED, I DONT EVEN LIKE DOING IT. THE PROBLEM IS THE CHAINS HAVE TO COME OFF ALONG WITH THE FRONT COVER AND EVERYTHING ATTACHED TO IT. YOU COULD REPLACE THE NOISY 1 IF ONLY 1, BUT WITH THAT MUCH LABOR I WOULD CHANGE BOTH. TO ISOLATE THE NOISE HAVE SOMEONE START THE ENGINE AND LISTEN WITH A MECHANICS STETHOSCOPE TO THE TOP FRONT OF EACH CAM COVER FOR THE LOUD 1, YOULL HAVE TO DO IT OVER SEVERAL ATTEMPTS SINCE IT SO SHORT.

 

Sounds like a fun job! Is there any harm to the engine by driving it with this condition?

My other question is, given the symptoms i posted, this VVT device sounds like the probable issue? In speaking to the service manager at our local dealer he said they had done a few of these 'anti-drainback' valves.

What actually fails?

Thanks,

BTW, where are you guys out of?

 

other than what youve described, I have never seen an engine damaged from a VVT noise, as far as what fails inside, I dont know as we cant diassamble when it gets sent back to Jaguar and product investigation. and since thats just more time spent for something we cant repair theres no incentive. Jaguar has also recommended increasing the oil viscosity for VVt issues,( case by case basis)try changing oil and use 10-40 or 20-50 and see if the noise stops.
Houston

 

Well I certainly do appreciate your comments. You've been more helpful than the dealer (of course). We did try changing the oil, but kept the 5w30 as specified in it. I remember it clattered exactly until the oil warning light extinguished. We live in northern new england, even now temps are falling into the 30's. Not sure if a thick oil is good, but I could try it temporarily.

Thanks again

 

Hi Brutal,

Spoke with the SM at the dealer again, the oil anti-drain back valve he was referring to is inside the VVT, so you are correct. However, he said the cost of parts along would be $1300! Plus probably another $1000 in labor! Holy cow, does this sound accurate? I would think only the VVT and accompanying seals would have to be changed, not all the timing chains and tensioners. If this costs upwards of $2500 I'm going to be REALLY upset that Rover didn't cover this under warranty when it happened at 39k miles. I would think there might still be some obligation for them to do so, since it is documented, but they and LRNA say no.

 

THE ONLY TIME I REPLACE ALL CHAINS ETC IS WHEN 1 HAS BROKEN, OR THE ENGINE HAS JUMPED TIME FROM A TENSIONER COMING APART. BUT SINCE IT IS A LABOR INTENSIVE JOB, I WOULD DO ALL TENSIONERS AND CHAIN GUIDES WITH BOTH VVT'S. BUT I CAN ALSO SAY IF ITWAS AN EXTENDED WARRANTY CO. THEY IN MOST CASES SAY TO ONLY REPLACE THE NOISY VVT, NOT BOTH UNLESS BOTH NOISY. AND EVEN THEN THIS IS 1 OF THOSE REPAIRS THAT THEYLL SEND AN INSPECTOR OUT ON AND THEN DENY THE CLAIM AS ITS A NOISE AND NOT A FAILURE. I HAVE ALWAYS BELIEVED IN TRYING THE EASIEST, CHEAPEST MOST LIKELY REPAIR BEFORE I SHOT GUN A JOB, BUT I ALSO PREFER TO TALK WITH THE CUSTOMER INSTEAD OF THE SERVICE ADVISOR STUMBLING THROUGH AN EXPLAINATION. PLUS IT LETS ME SET EXPECTATIONS, AND MOSTLY TO BUILD CONFIDENCE IN THE CUSTOMER AND PUT A FACE ON WHOS WORKING ON THEIR VEHICLE, RATHER THAN THINKING IT JUST GOES INTO SOME BLACK HOLE BACK THERE ONLY TO EMERGE AT SOME POINT LATER IN TIME. SO BACK TO MY ORIGINAL RECOMMENDATION INCREASE THE OIL VISCOSITY OR YOU COULD EVEN ADD 2-3 CANS OF STP ENGINE TREATMENT TO SEE IF THIS ALLEVIATES THE NOISE. IF NOT YOURE ONLY OUT A FEW BUCKS INSTEAD OF $2500, WHICH CAN ALWAYS BE SPENT LATER......BUT ITS YOUR MONEY AND YOUR VEHICLE, LET ME KNOW

 

I have never seen an engine with this anti drainback valve in the oil supply system. This would make the whole thing a one way system and this just doesn't make engineering sensedue to a potential destructive suction behind the valve on sudden deceleration and corresponding hammer on reacceleration. The guys that told you this either don't know how it works or you misunderstood them. What you possibly haveis aVVT thatis leaking internally at the o-rings and losing pressure.Itmight need to be replaced if you want it perfect. The secondary tensioners are spring loaded, this is what keeps them from rattling at start-up. It is also possible that for some reason, you have a chain guide that has cracked (common), allowing the primary chain to sag a little. The primary tensioners are set upwithwedges to keep the chain tight during installation, but if the guide cracks, it can get a little loose.This is front cover-off check.

 

OK, here is an update, after a month. We took the car to our Mercedes mechanic who also works on plenty of Jaguars. He is meticulous and has always done a good job on our Mercedes, so why not? His diagnosis was that the secondary tensioner on the driver side failed, causing slack in the chain, which caused the rattle at startup until pressure was restored. He changed the tensioner on that side, and the short chain, and whatever else was required. Today we received word after sitting over the weekend it still made a rattle at startup, just quieter than usual. He said with the original short chain on, there was definitely slack. The new chain eliminated the slack, but there is still noise! I'm guessing now the problem is in the VVT? How could changing the tensioner and chain alleviate the problem, then, if the VVT is still the problem? Does anyone have a diagram or shop manual page showing the relationship of the tensioners, VVT, and chain? Not happy, we have not had the car for nearly 2 months now.

 

I have seen the lower tensioner/guide cause a rattling problem as well, but very few VVT's cause it. Have you used a stethoscope to locate where the noise eminates?

 

Well, we talked to our mechanic again, and he thinks the problem is, in fact, solved. The noise it makes now is not as noticeable as before, and he thinks it is due to the new chain being tight and not 'worked in' just yet. He is going to drive the vehicle a few times to cycle the chain, as he puts it, and he is confident this will clear up the problem. He is using a chain with a removable link to save time on installation, and he says this type of chain is a slightly tighter fit than the standard chain, but it will be fine. We will hear from him again on Wednesday, I'll update then.

 

I am only guessing here, but the oil flow to the VVTisthrottled by a solenoid valve in the cam cover. You might have a worn valve that is not holding pressure, you could try another known good one to see if this is the problem. There is no test I know of. These valves are way easier to change than the VVT unit and its bush. I think this is the one way valve your tech is talking of.

 

I should have mentioned that if you check out the solenoid valve, be sure to check the harness and make sure there is power to the valve. These harnesses can get damaged.
I do not know what is inside the VVT because they are not suposed to be repairable at home, but the way they work, I tend to doubt that there is any one way valve in them, they shouldhave no need to hold pressure themselves, there would be no control over it and they could not disengage, they would just always be engaged.The oil pressure controlwould have to beheld by the electrically activated solenoid so it can disengage when the cam needs to reset. This is the likely weak link.

 

Tensioners / Chains have different symptoms from VVT unit/ solenoid valve function.
1.Tensioners / Chains Most probable cause
Ticking noise that is heard on intial COLD start up caused by the chain slaping on the Upper tensioners. If this noise last a 5 to ten seconds Do Not Worry about it. If the Noise last a couple of minutes it is STILL the Chain slaping on the upper tensioners __ This will eventually Result in a FAILURE of the WEAR PAD on the UPPER tensioners. THE Ticking Noise will Last longer and Longer.

If the Ticking Noise seems to be coming from the timing chain cover area and is more constant after the engine is warmed up -The timing chain guides are cracked.

THE Above conditions will not give you a check engine light or code....... until the TENSIONER FAILS and Results in an ENGINE FAULT.

2. VVT/solenoid Valve. -This affects engine performance and milage
About 2 minutes after the Vehicle is started. The EMS/computer will activiate the VVT Solenoid.Valves on both banks...
OPEN the Bonnet/Hood START the engine - WITHIN 2 Minutes -STAND NEAR the front of the engine and listen carefully you should hear a very AUDIBLE CLICK or CLACK THAT CLACK is the opening of the Solenoid supplying oil pressure to the VVT UNITs.

THE VVT UNITs control the cams for improved engine performance

If the VVT unit is not properly functioning or the Solenoid does not operate within 2 minutes you should get a Check engine Light and Fault Code.. Sometimes the code will not show til you have driven wiith a little hard throttle.

GOOD LUCK












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