# Jaguar s-type rough idle **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** jaguar, timing-belts, s-type\ **Created:** [April 21, 2015, 12:59am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723 "2015-04-21T00:59:30Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![seagates5](https://avatars.discourse-cdn.com/v4/letter/s/e480ec/32.png) [@seagates5](https://community.cartalk.com/u/seagates5)\ **Post date:** [April 21, 2015, 12:59am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/1 "2015-04-21T00:59:30Z")
I have a 2001 jag stype v8 with 180k miles. I bought the timing kit and aligned the camshafts correctly but it still idling rough and sounding like a diesel truck. Anyone have any ideas as to what still maybe the problem? ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [April 21, 2015, 1:07am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/2 "2015-04-21T01:07:31Z")
Have you done a compression test? Have you put a vacuum gage on it? The “diesel truck” sound suggests a valve problem. ---
**Author:** ![seagates5](https://avatars.discourse-cdn.com/v4/letter/s/e480ec/32.png) [@seagates5](https://community.cartalk.com/u/seagates5)\ **Post date:** [April 21, 2015, 4:05am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/3 "2015-04-21T04:05:18Z")
Yea I did the compression was 130-135 on all 8 cylinders ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [April 21, 2015, 7:51am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/4 "2015-04-21T07:51:32Z")
Is the exhaust system in good shape from the exhaust manifold to the tail pipe? Leaks in the exhaust system can cause both symptoms. ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [April 21, 2015, 8:14am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/5 "2015-04-21T08:14:19Z")
Thsoe compression numbers are low. I would suggest that the test be done again using the wet version; meaning a small squirt of oil in each cylinder before it’s retested. If the numbers jump up by a fair amount there’s a piston ring/cylinder wall issue. If they stay about the same then it’s a cylinder head valve issue. That’s all assuming cam timing is dead on, etc. That may or may not be the cause of the rough idle as a number of things could be responsible for that. Vacuum leak, weak valve spring, ignition miss, fuel injector, etc, etc, etc. The noise could possibly be excessive valve lash which could also cause a rough idle if loose enough or it could be related to the timing chain tensioner which is allowing the chain to rattle. It’s impossible for me to know if the noise is up top or down low. ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [April 21, 2015, 9:37pm UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/6 "2015-04-21T21:37:02Z")
^ +1 Assuming compression ratio is 8-9:1 I’d expect 160-180 psi. ---
**Author:** ![insightful](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/insightful/32/2732_2.png) [@insightful](https://community.cartalk.com/u/insightful)\ **Post date:** [April 22, 2015, 6:15am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/7 "2015-04-22T06:15:17Z")
> I bought the timing kit and aligned the camshafts correctly but it still idling rough and sounding like a diesel truck. Did it have these symptoms before the new timing kit? ---
**Author:** ![seagates5](https://avatars.discourse-cdn.com/v4/letter/s/e480ec/32.png) [@seagates5](https://community.cartalk.com/u/seagates5)\ **Post date:** [April 22, 2015, 6:58am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/8 "2015-04-22T06:58:19Z")
Yea it was doing it before the timing kit… I did a vacuum test and it was reading a shaky 16.5-16 in.Hg… I havent checked the valve lash but thats my next step… I also made to a video of[engine running](https://www.youtube.com/watch?v=G4gKF02sfik) and the [vacuum test](https://www.youtube.com/watch?v=0H4wbkIwLR0) ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [April 22, 2015, 7:21am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/9 "2015-04-22T07:21:30Z")
If the vacuum was unstable, you either have a vacuum leak or a valve problem. My money is on the valve problem. ---
**Author:** ![insightful](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/insightful/32/2732_2.png) [@insightful](https://community.cartalk.com/u/insightful)\ **Post date:** [April 22, 2015, 11:34pm UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/10 "2015-04-22T23:34:54Z")
So, has it ever idled smoothly and quietly while in your possession? What I’m getting at is do you have any idea what (if any) changes occurred coincident with the onset of symptoms. If you bought it like this, sounds like you bought a trashed engine that’s probably gonna have to come apart. ---
**Author:** ![seagates5](https://avatars.discourse-cdn.com/v4/letter/s/e480ec/32.png) [@seagates5](https://community.cartalk.com/u/seagates5)\ **Post date:** [April 24, 2015, 12:15pm UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/11 "2015-04-24T12:15:25Z")
No it I bought it with a rough idle but it was quiet. I bought knowing it was gonna need some work, I was hoping for it to be not as bad as I thought. I think it might be the intale valves on thr driver side. I checked all the valve lashes on the exhaust and intake valves and they all are within spec except the driver intake valves. They were all inconsistent ---
**Author:** ![insightful](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/insightful/32/2732_2.png) [@insightful](https://community.cartalk.com/u/insightful)\ **Post date:** [April 25, 2015, 2:36am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/12 "2015-04-25T02:36:11Z")
> I bought it with a rough idle but it was quiet. So the noise started with the timing kit, right? ---
**Author:** ![seagates5](https://avatars.discourse-cdn.com/v4/letter/s/e480ec/32.png) [@seagates5](https://community.cartalk.com/u/seagates5)\ **Post date:** [April 27, 2015, 1:27am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/13 "2015-04-27T01:27:07Z")
It started jus right before I bought the kit but after I bought the car ---
**Author:** ![insightful](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/insightful/32/2732_2.png) [@insightful](https://community.cartalk.com/u/insightful)\ **Post date:** [April 27, 2015, 2:11am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/14 "2015-04-27T02:11:25Z")
> I checked all the valve lashes on the exhaust and intake valves and they all are within spec except the driver intake valves. They were all inconsistent Please list those “inconsistent” valve clearances (along with the specs). ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [April 27, 2015, 4:20am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/15 "2015-04-27T04:20:20Z")
If the valve clearances on the driver side intake valves are out of spec, what makes you think the symptom isn’t caused by that? Are they just slightly out of spec then? ---
**Author:** ![seagates5](https://avatars.discourse-cdn.com/v4/letter/s/e480ec/32.png) [@seagates5](https://community.cartalk.com/u/seagates5)\ **Post date:** [May 1, 2015, 10:35pm UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/16 "2015-05-01T22:35:59Z")
Passenger Exhaust .28mm on all 8 Passenger Intake .24mm on all 8 Driver Exhaust .27mm on all 8 Drive Intake .19mm .19 .23 .23 .23 .20 .20 The intake valves are supposed to be .18mm to .22mm clearance The exhaust valves are supposed to be .23mm to .27mm clearance ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [May 2, 2015, 12:03am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/17 "2015-05-02T00:03:03Z")
A hundredth of a millimeter out of spec is meaningless and there’s nothing there to worry about. ---
**Author:** ![seagates5](https://avatars.discourse-cdn.com/v4/letter/s/e480ec/32.png) [@seagates5](https://community.cartalk.com/u/seagates5)\ **Post date:** [May 2, 2015, 3:31am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/18 "2015-05-02T03:31:09Z")
Is it still possible to have a bent valve with those clearance values? ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [May 2, 2015, 3:38am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/19 "2015-05-02T03:38:38Z")
When a valve stem gets bent the lash increases and usually by quite a bit. It often comes across as a loud metallic and comparatively tinny knocking sound. Based on those specs I don’t see an issue with it. ---
**Author:** ![seagates5](https://avatars.discourse-cdn.com/v4/letter/s/e480ec/32.png) [@seagates5](https://community.cartalk.com/u/seagates5)\ **Post date:** [May 2, 2015, 4:11am UTC](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723/20 "2015-05-02T04:11:41Z")
It does make a loud metal ticking noise. On the first page I posted 2 vids, one of a vacuum test and the other of just the motor running. [Next page](https://community.cartalk.com/t/jaguar-s-type-rough-idle/89723.md?page=2)