The Jensen Owners' Club A technical and discussion forum for all Jensen enthusiasts It is currently Wed Oct 24, 2018 1:42 am

V-8 Engine Tech

Nasty sound - wot's 'appening?

Mopar Big Block Talk

by Per » Sat Jan 20, 2018 10:12 pm

All, the FF makes a nasty noise, info as follows:

- Tinny, clattery noise with a frequency following engine rpm
- Only comes in once engine is above 80C, and disappears again if tem falls below 80C
- When listening with a rod stethoscope the noise is strong and clear at the rear of block where the valley pan is bolted down with a clamp and three small hex head bolts. Equally strong at the oil pressure low switch right at the rear of the block. And nearly as strong at the very rear of the valley pan itself.
- Oil changed
- Lifters replaced
- Oil pressure is 80 psi cold, ca 45psi hot at idle and 80 psi at say 2000rpm
- Oil pressure needle vibrates a bit at all times, when the clattering is there it fluctuates very quickly with ca 30psi peak-to-peak at idle. With rising revs the frequency increases and peak-to-peak reduces to ca 10psi at 3000psi

Otherwise the engine runs beautifully, idles nicely, pulls strongly, responds well to the throttle.

Any ideas what is happening
Per
Only English cars these days, need to make room for an Italian again 8)
User avatar
Per
 
Posts: 2532
Joined: Thu May 18, 2006 5:12 pm
Location: Norway

by Keith » Sat Jan 20, 2018 10:38 pm

Your exhaust manifold gasket is blowing.
Forum Founder & Forum Member No 1.
User avatar
Keith
 
Posts: 5265
Joined: Thu Oct 13, 2005 9:19 pm
Location: Further up the creek!

by Per » Sat Jan 20, 2018 10:48 pm

Nope, copper gasket and when I pulled it there was no trace of a leak at all. I.e. no tell tale black tracing.
Per
Only English cars these days, need to make room for an Italian again 8)
User avatar
Per
 
Posts: 2532
Joined: Thu May 18, 2006 5:12 pm
Location: Norway

by slotcarone » Sun Jan 21, 2018 5:33 am

Check the torque converter bolts--they could be loose! :)
1972 Interceptor III
133-5612
User avatar
slotcarone
 
Posts: 443
Joined: Sun Aug 29, 2010 1:38 pm

by Steve Payne » Sun Jan 21, 2018 4:16 pm

Cracked exhaust manifold or downpipe gasket?

Steve
JOC official Lightning engineer
User avatar
Steve Payne
MASSIVE RED CARD
MASSIVE RED CARD
 
Posts: 4979
Joined: Thu Nov 17, 2005 4:51 pm
Location: Witney , Oxfordshire

by Chris_R » Mon Jan 22, 2018 10:26 am

Per wrote:All, the FF makes a nasty noise, info as follows:

- Tinny, clattery noise with a frequency following engine rpm
- Only comes in once engine is above 80C, and disappears again if tem falls below 80C

- Oil pressure is 80 psi cold, ca 45psi hot at idle and 80 psi at say 2000rpm
- Oil pressure needle vibrates a bit at all times, when the clattering is there it fluctuates very quickly with ca 30psi peak-to-peak at idle. With rising revs the frequency increases and peak-to-peak reduces to ca 10psi at 3000psi


Those oil pressures are in my opinion excessive. You should have 45 - 65 psi when hot at 1,000rpm on an SAE40 grade of oil. Increasing engine speed should not increase oil pressure further, the pressure relief valve should regulate that.
A fluctuating oil pressure needle indicates either a fault in the oil pressure sender or gauge or it really is indicating a fluctuating oil pressure as it builds up and is then suddenly released. A sticky pressure relief valve in the oil pump would give that symptom. You should validate the pressure fluctuation with a directly connected pressure gauge.
But picking up on the location of the noise which seems to be linked to the fluctuations and with such high oil pressure could it be possible that one (or more) of the lifters is venting all its oil resulting in a gap for the push rod until the oil is replenished in the lifter until it squirts out again? If the lifters have insufficient oil there would be a noise on the pushrod. Such an action could cause the sound and could also cause a fluctuating oil pressure as oil fills the lifter and then is squirted out uncontrolled.
It wouldn't do it when cold because the oil is too thick but once it thins out when hot then it could happen. A fluctuating pressure indication could cause damage elsewhere as when the pressure drops momentarily it could lead to a flow reduction and consequent starvation elsewhere.
Chris
JOC Member 6116
--------------------------------------------------
User avatar
Chris_R
 
Posts: 4807
Joined: Sun Feb 10, 2008 9:19 am
Location: South West London

by RockyUSA » Mon Jan 22, 2018 1:37 pm

With the (electrical) oil pressure senders typically installed in our cars, I would be very surprised to see that kind of instantaneous response as described by the OP.

I certainly agree with Chris that you should get a real independent mechanical gauge on it, to confirm what you think you are observing.

Rocky.
'72 Interceptor III - 133/5597
'73 DeTomaso Pantera
'74 Toyota Land Cruiser FJ-40
'95 Jaguar XJS Convertible
User avatar
RockyUSA
 
Posts: 584
Joined: Sun Jul 03, 2016 10:10 am
Location: Tucson, Arizona, USA

by Per » Mon Jan 22, 2018 2:11 pm

The gauge is mechanical, the sensor for the lamp is electrical.
Per
Only English cars these days, need to make room for an Italian again 8)
User avatar
Per
 
Posts: 2532
Joined: Thu May 18, 2006 5:12 pm
Location: Norway

by RockyUSA » Mon Jan 22, 2018 3:44 pm

That explains the fast response of the gauge.

Rocky
'72 Interceptor III - 133/5597
'73 DeTomaso Pantera
'74 Toyota Land Cruiser FJ-40
'95 Jaguar XJS Convertible
User avatar
RockyUSA
 
Posts: 584
Joined: Sun Jul 03, 2016 10:10 am
Location: Tucson, Arizona, USA

by Per » Wed Jan 24, 2018 9:55 pm

OK, checked and rechecked since last mail:
- Torque converter bolts tight
- Oil pressure relief spring etc OK

I have revisited the pressures and 45 - 50 psi at idle is just right as is (warm) 80 at about 1500 upwards for 80C temp. (Checked on various mopar forums.)

So:
- Oil pump is at the opposite end of the noisy area.
- When warm the pressure needle flickers a bit but is rock steady at 80psi once rpms are a bit above 1500.
- When oil is hot (water temp above 88C) the noise starts and pressure flicker wildly as related previously.

From this I believe the pump delivers as it should. If it was the pump it would struggle to keep pressure up but needle would not flicker unless the pump was really damaged and then it would give off some sort of noise. If the suction side was blocked by debris (e.g. from the timing gears) I still do not see why that should cause rapid flickering with frequency following engine speed without fail.
Moreover I am now convinced it is a tappet(s) being oil starved or leaking down too fast that I hear. NB! Tappets have been renewed.
Thus there is a leak down somewhere which is pulsing. A natural candidate might be a rocker arm generally leaking a bit and when hitting the oil hole leaking a LOT!? There are no untoward noises so I do not believe the main or big end bearings are the cuprits.

Comments?
Per
Only English cars these days, need to make room for an Italian again 8)
User avatar
Per
 
Posts: 2532
Joined: Thu May 18, 2006 5:12 pm
Location: Norway

by Keith » Wed Jan 24, 2018 10:11 pm

Per wrote:Comments?


Your exhaust manifold gasket is blowing.
Forum Founder & Forum Member No 1.
User avatar
Keith
 
Posts: 5265
Joined: Thu Oct 13, 2005 9:19 pm
Location: Further up the creek!

by Per » Wed Jan 24, 2018 10:23 pm

No, no and no Keith! As I mentioned I have already pulled it and no trace whatsoever on the copper gasket. Anyway It would not start blowing above 88C and immediately stop when below. Particularly not with a copper gasket which has a higher thermal expansion rate than cast iron and steel.
Per
Only English cars these days, need to make room for an Italian again 8)
User avatar
Per
 
Posts: 2532
Joined: Thu May 18, 2006 5:12 pm
Location: Norway

by AH1951 » Wed Jan 24, 2018 10:47 pm

Per wrote:No, no and no Keith! As I mentioned I have already pulled it and no trace whatsoever on the copper gasket.


You're supposed to have TWO!
:)

Can I pop over on Sunday afternoon and listen?
I'm just next-door.
Ex-owner Jensen FF Mk II No.304
Present car: Bentley Flying Spur
AH1951
 
Posts: 3173
Joined: Thu Oct 24, 2013 5:07 pm
Location: Jakarta

by Per » Thu Jan 25, 2018 5:20 am

Well yes them not it ☺

You are welcome to listen but depending where you are it is between one hour and two days from Sweden. I can offer a cup of coffee though .....
Per
Only English cars these days, need to make room for an Italian again 8)
User avatar
Per
 
Posts: 2532
Joined: Thu May 18, 2006 5:12 pm
Location: Norway

by johnw » Thu Jan 25, 2018 2:33 pm

To rule out exhaust gasket leaks, how about removing spark plugs from pairs of cylinders???
The two back ones on each side, see if the noise changes.
--
John Wild
Working on: LHD 1973 Mk3 Interceptor J series, 119/122.
Previous FFs: 119/006, 119/73, 119/123, 119/132, 127/255, 127/289. Current: 119/036 (remains stolen unrecovered).
User avatar
johnw
 
Posts: 226
Joined: Wed Sep 15, 2010 7:38 pm

Next

Return to V-8 Engine Tech