vvt solenoid rattle
#1
10-17-2008, 07:50 AM
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vvt solenoid rattle
Hi, my first post here and need some help if possible. I have a 1999 xk8 and i have a weird rattle coming from the VVT area.
Little history, car has 84k on it with a replacement engine in 2003 which has done 20k according to its service records. I had 2 rattles, one being the tensioners problem which i had replaced, one rattle gone, 2nd rattle seemed to be coming from top front of engine. This was diagnosed as being the VVT valves by two jag garages.
I had the VVts replaced but have still got said rattle, symtoms of which are, when the car is revved, on the down rev, under 1000 revs to rest a rattle is heard from the VVT area on both sides.
Bit of investigating, i have found that with engine running, if i remove the power plug to the VVt solenoids and then replace the plug straight away, the rattle goes and is not heard again until the engine is turned off and back on again.
I replaced the solenoids with second hand ones and still get the rattle.
Has anyone else had the same symtoms and found a cure?.
Not being a mechanic im guessing at maybe to much electric current is going to the solenoids, is this posible?
This only happens when engine is hot, not from cold start.
Any comments appreciated.
Little history, car has 84k on it with a replacement engine in 2003 which has done 20k according to its service records. I had 2 rattles, one being the tensioners problem which i had replaced, one rattle gone, 2nd rattle seemed to be coming from top front of engine. This was diagnosed as being the VVT valves by two jag garages.
I had the VVts replaced but have still got said rattle, symtoms of which are, when the car is revved, on the down rev, under 1000 revs to rest a rattle is heard from the VVT area on both sides.
Bit of investigating, i have found that with engine running, if i remove the power plug to the VVt solenoids and then replace the plug straight away, the rattle goes and is not heard again until the engine is turned off and back on again.
I replaced the solenoids with second hand ones and still get the rattle.
Has anyone else had the same symtoms and found a cure?.
Not being a mechanic im guessing at maybe to much electric current is going to the solenoids, is this posible?
This only happens when engine is hot, not from cold start.
Any comments appreciated.
#2
10-17-2008, 09:54 AM
RE: vvt solenoid rattle
Based on what you said, it sounds like lack of lubrication. if you are using 5w20 oil, try going to 10w30 and make sure you fill to the top mark on the dipstick. If the oil pump is not putting out the needed pressure at low RPM (Below 1000) thicker oil might help for a while, but you'll need a new pump eventually.
You stated it only happens when the engine is up to operating temperature. The oil has a much lighter viscosity at operating temp, that's why I suspect the oil pump.
You stated it only happens when the engine is up to operating temperature. The oil has a much lighter viscosity at operating temp, that's why I suspect the oil pump.
#4
10-17-2008, 10:29 AM
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RE: vvt solenoid rattle
Thanks for the welcome,
The oil answer is an interesting one, ill check that out thanks. I do find it strange that when i remove the power connections for a few seconds and re attach the rattle goes. I presume the vvts are still working when the electrical power is re connected but im not sure, the car doesnt feel any different when driven.
Ive been in touch with lots of garages today and no one has heard of this problem, although 1 has mentioned that changing the solenoid carriers might solve it and another is looking at the temperature feed from the ecu to the solenoid, or something like that, he lost me a bit.
Hmmm, nope no relation
ps: can i mix the oil? top up if necassary with the 10 oil?
The oil answer is an interesting one, ill check that out thanks. I do find it strange that when i remove the power connections for a few seconds and re attach the rattle goes. I presume the vvts are still working when the electrical power is re connected but im not sure, the car doesnt feel any different when driven.
Ive been in touch with lots of garages today and no one has heard of this problem, although 1 has mentioned that changing the solenoid carriers might solve it and another is looking at the temperature feed from the ecu to the solenoid, or something like that, he lost me a bit.
Hmmm, nope no relation
ps: can i mix the oil? top up if necassary with the 10 oil?
#5
10-17-2008, 01:36 PM
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Location: Powell, Ohio U.S.A. 43065
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RE: vvt solenoid rattle
The AJ27 oilpump is a higher volume than the AJ26: in fact, the later pump has superceded the earlier one.
If the engine replacement was an overhauled unit from an outside supplier,perhaps it has the early pump installed. The upgrade was necessary to maintain proper oil pressure for the later style V V T units, fitted 1999 on (AJ27).
If the engine replacement was a used unit, perhaps it is an AJ26 engine that was outfitted to fit your later car...but the oil pump wasn't updated.
I haven't come across an engine with a rattle that was caused by a V V T unit: I'm sure it's possible, but my opinion is that most times they are condemned (or replaced) without verification.
Bottom line is that if the timing cover comes off your engine, replace the oil pump before you reassemble it. The cost is less than $400, and the extra work involved is five minutes if the primary chains are alreadyremoved.
If the engine replacement was an overhauled unit from an outside supplier,perhaps it has the early pump installed. The upgrade was necessary to maintain proper oil pressure for the later style V V T units, fitted 1999 on (AJ27).
If the engine replacement was a used unit, perhaps it is an AJ26 engine that was outfitted to fit your later car...but the oil pump wasn't updated.
I haven't come across an engine with a rattle that was caused by a V V T unit: I'm sure it's possible, but my opinion is that most times they are condemned (or replaced) without verification.
Bottom line is that if the timing cover comes off your engine, replace the oil pump before you reassemble it. The cost is less than $400, and the extra work involved is five minutes if the primary chains are alreadyremoved.
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