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You could, but my fix or a version of it would be better IMO, as that keeps the idle control bolt functional. If you look down the entry tube of the AAV, you can see where the idle take off is. Blocking the AAV passage after this take off would do it. If you want ideas on how to do this safely, AAV in situ, post again.You would of course have to hold the revs when cold on the throttle for a minute or two. Also, very important, permanently blocking off the AAV air feed (other than as I mention here) will also permanently block off the dizzy ventilation, which you should NOT do.
My blockage idea was just to prove whether or not the AAV was the problem. As you seem to have proven that it is, see answer 2 for my recommendation, other than removing the AAV for the Grant fix, that is!
I think that 6 minutes is plenty long enough for a working AAV to close completely, so I suspect your AAV is not working well at all.
Respect to the GF for her idea, maybe she should do the car and you do the indoor stuff!!??
(1) At what RPM would you be happy to drop a V12 XJS into gear
Under 1000 for sure, as Greg says 850 would be better.
First of all in response to Jagboi's Question: I'm using 10/40 Semi Synthetic
That's good, although a 0W-40 would be better if you can find it. The general rule is have the first number low as possible, so either 5 or 0, and the second number use whatever the manufacturer recommends.
The Next bit is from memory but I Video'd the whole thing and so the figures I'm giving you now may not be accurate and also the Oil Pressure almost certainly took less than 10 Seconds as hopefully the Video will Show when I get it put up Oil Light probably went out at 6 Seconds but I didn't get that on Video (Now Updated)
6 seconds is about right. Obviously shorter is better.
In a decent engine they should - with modern lubricants some of this hi RPM start stuff may be justified in an engine that is run regularly, the V12 however is not modern, some of these cars spend extended periods of non running so you can't always rely on an oil film get out of jail.
I actually asked Ford why my Jaguar V8 did the high RPM thing - the response was 'it adds to the theatre' - there is no solution, well their may be but they declined to provide one.
I used to work for a company that packaged oilfield equipment and I analyised medium HP engines - 1500-2000hp. These didn't have prelube circuits, as the smaller engines didn't have a provision for it. Tests were done to measure bearing wear of the two scenarios of cranking without starting to build oil pressure first and then start, or starting right away and letting oil pressure build naturally with the higher revs. In all tests, it was found that engines that were started right away had less wear. For these engines anyway, it took more revolutions to get oil up to the top of the engine and circulating at cranking speed than at higher speed. The oil pumps were less efficient at lower RPM and didn't pump as much oil due to the lower pressure developed.
Where possible, engine preheating (i.e. a block/oil heater) was used at temperatures below 10°C and that helped oil pressure build much quicker. Without prelube, the best situation is preheating, followed by starting right away and avoiding extended cranking.
I suspect the answer you got from Ford was from the PR department, without any input from the Engineering department!
Of course, the industrial engines are designed for a much longer lifespan than automotive engines, and have a very different load profile; as they are designed to run at full throttle 24/7. Automotive duty engines are not, and are considered "throw away" engines in comparison. Mind you, they don't cost $2 million for a long block either....
Alex
Attached the famous Picasso sketch this shows how the AAV works and how the idle speed adjuster comes off earlier in the air entrance than the AAV air entry. Also the photo below shows where the idle speed canal hole is. Take some of this stuff:
Get the hair dryer on the AAV so it is as closed as possible, Shove a thin split pin or similar down the tube and right through the AAV hole to the other side of the barrel. Then shove the putty down the hole ensuring it does not block the idle speed hole. The split pin/nail is there to give the putty something to adhere to, and also ensure the end of the pin goes right through the AAV hole in the barrel to the other side of the barrel. This ensures the putty has a bit of steel in its centre taking the suction load. Leave it the requisite 24 hours to set. Start car, warm up engine, set idle speed with bolt on AAV as normal. Sorry about the focus, the arrow points to a just-visible hole that leads down to the idle speed adjuster canal. The bung needs to be downstream of this hole.
Of course, all this is easier with the AAV off the car! The impact gun will do the bolts OK.
After a Stone Cold Start Up, how long would you expect to wait to get to the Magic 850 RPM or would you expect 850 RPM immediately after Start Up
I was able to adjust my AAV to give around 900 after a cold start and drop to 650 when warm. I usually start the car, then put on my seatbelt, wait for the oil pressure gauge to come up and show a reading and by that time it's dropped enough to be ready to go. Mine also has an air injection pump, when that shuts off the revs will drop a fair bit. It's noticeable when it shuts off.
I think I've also got an Air Injection Pump on mine, as after a while the Revs just drop away, although I don't like to keep her idling for to long, especially at £9 for 5 Litres!
I don't like to keep her idling for to long, especially at £9 for 5 Litres!
I know what you mean, I just came back from a holiday in England. Fuel here in Canada is the same number per litre (1.70), just in Canadian dollars, not pounds! Although I fueled up at Costco and it was £1.55 per litre.
The air injection pump on mine is clutched like an AC compressor and kicks off after 45 seconds, so it's not a lot of idling.
I think I've also got an Air Injection Pump on mine, as after a while the Revs just drop away, although I don't like to keep her idling for to long, especially at £9 for 5 Litres!
Just to wrap this thread up. In the end I decided to use jonas aka the jag improver rebuild kit for the aav. He told me not to push the top hat in. I left things as they were from factory and replaced the bulb , spring and piston after cleaning. She fired up and ticked over at 900 rpm from cold dropping to around 700 when at temperature. Perfect, no hunting job done. I queried that the piston did not fully retract from view when cold and jonas explained it would recede more as the ambient temperature dropped which makes sense. Pleased with the results and only need to sort the abs light and she’s ready for an mot.!
Struggling with a link Greg. Search for jagimprover on eBay. I have had stuff from Jonas before like extra long oil feed bolts and aluminium half moons. He's good but not cheap.
05-25-2022, 11:50 AM
