Nasty sound - wot's 'appening?

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Per
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Re: Nasty sound - wot's 'appening?

Post by Per »

Simple double check that so worth it.
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Re: Nasty sound - wot's 'appening?

Post by Per »

Ok I am convinced that there is a leakdown somwhere. And the feed to the leaky area is via crankshaft or camshaft resulting in a dip in pressure when the feed hole aligns with the corresponding hole in the rotating part.


The test to identify the area is to run the oilpump with a drill. Then rotating the crankshaft slowly. When the dip comes the position of the rotating parts tells which area is the culprit.
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Re: Nasty sound - wot's 'appening?

Post by Per »

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Hmmm, I wonder if the oil pump is the cause after all or if I have two independent problems. Pulling the oil pump drive shaft today look at the hex end!

Pump out is next for sure.
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Re: Nasty sound - wot's 'appening?

Post by DaveAK »

Definitely worth looking at that pump. I've got one of those drive shafts that's missing the hex end - and two bent con rods because of it. :(
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Re: Nasty sound - wot's 'appening?

Post by Per »

The pump is by a gnat's whisker within spec using feeler gauges, however.....
Rotating parts are scored, either from running dry some time in the past or without filter ditto. So replacement is necessary. In addition the axle shaft hex has a lot of play in the hex hole in the rotor. More than seems reasonable to me?
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Re: Nasty sound - wot's 'appening?

Post by Per »

Melling HVNP pump and new shaft ordered. And I have modified (read removed the cogwheel) the old shaft in combination with a wrecked dizzy so now I can run the pump with a drill. Pump is due here in a couple of weeks. It was -17C yesterday morning so too cold for fumbling with machinery in an unheated garage anyway.
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Re: Nasty sound - wot's 'appening?

Post by cannonball »

Per wrote:Melling HVNP pump and new shaft ordered. And I have modified (read removed the cogwheel) the old shaft in combination with a wrecked dizzy so now I can run the pump with a drill. Pump is due here in a couple of weeks. It was -17C yesterday morning so too cold for fumbling with machinery in an unheated garage anyway.

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Re: Nasty sound - wot's 'appening?

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Thanks yes, I have even written a note with engine and dizzy direction and taped it to the windscreen. I don't trust my memory one jot in these things :oops: :lol:
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Re: Nasty sound - wot's 'appening?

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I have fitted a new pump and get 80psi cold. HOWEVER when turning on starter there is a distinct drop to about 60psi at a frequency which corresponds well with every two revs on the crank i. e. once on the camshaft. That the feeding of one bank of rockers etc. should cause such a drop each time the feed from the camshaft overlaps with the feed hole seems excessive to me. If somebody could check on their engine it would be appreciated.

NB best view is with old type slow starter and of course a long churn so that oil pressure builds up. And direct analog pressure gauge not electrical type as these are to sliw in response.
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Frank Schwartz
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Re: Nasty sound - wot's 'appening?

Post by Frank Schwartz »

This may be a bit far out, but there are right hand and left hand rockers..are yours properly placed???

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Re: Nasty sound - wot's 'appening?

Post by johnw »

Could a greedy, noisy, hydraulic tappet be causing the drop, as is passes the oil feed hole? The noise you described wasn't coming from the oil pump drive by the sounds. It could be that your tappets are worn, and the pump scoring is from follower surface debris. Unlikely but it could be a tooth on the cam missing causing the oil pressure to cyclically falter. More likely missing teeth from the nylon cam sprocket. As the tappets wear the oil feed timing presumably changes? Also Mike said a previous owner tuned the car and that the owner did the quarter mile in 14.5 seconds. Visually I remember the car had 440 style manifolds on it and alloy rocker covers. Basically the cam might be more aggressive than stock, putting more wear on the valve gear and tappets.

I am NOT an expert but things to consider. Apparently one possible problem with high volume oil pumps on Mopar engines is the oil drain back or lack of, the pump can sometimes keep the heads/top end full of oil, as the volume of oil shifted is greater than the drainback capability if you have worn rockers etc, the engine smokes as the valve guides have too much oil to deal with, then the pump then cavitates as the sump oil level is low. Perhaps you need a high capacity sump and oil return can be improved by drilling out the oil return ways and making sure there are no casting defects.

Because it is a high volume oil pump it requires correspondingly more torque to turn, and you probably need a strengthened shaft, not just a new stock one. I guess you got the improved drive? Also on the FF, I think there may be a clearance issue with larger high volume oil pumps and the left hand chassis leg. Did you manage to fit it OK? Also with higher volumes, the filter is more likely to get bypassed, leading to unfiltered bits from the failing tappet getting through.

Have you checked the bronze oil pump drive bush in the block for wear, BTW?

I have had a standard pump drive shear while doing 70 on the motorway. First you hear the tappets, then you see the mechanical gauge sinking slowly to 0. :shock: Took a couple of seconds for all the pressure to dissipate. The FF was heavy enough to coast off and up a slipway in neutral with the engine off, no damage apart from the drive. The pumps are often badly scored. If it is within spec it should be doing its job. I am not saying run with a scored pump, but that the scored pump is not the cause in my view. Thankfully you have a new pump drive shaft, as I suspect a tight new pump can shear an old tired drive...
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Re: Nasty sound - wot's 'appening?

Post by Per »

Lots of food for thought there John. The tappets were replaced as part of the initial work to cure the problem. They all were within specs as it turned out and no scoring. The bronze bushing for the pump drive shaft is good as well. The old pump was HVNP as is the new one. No probs replacing with LH mount undone and engine jacked up.

Will run it nice and warm today and expect the problem to be there still.

If it was oil starvation at the pump I would expect a permanent pressure drop during that condition and not a rythmic drop building up in amplitude as temp goes up.
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Re: Nasty sound - wot's 'appening?

Post by Frankoid »

What oil filter have you Per? I was only getting 5 psi hot in my FF so I put a washer behind the oil pressure spring in the pump and the pressure went off the dial, the oil filter blew up like a balloon and burst.. :shock: I have now sourced an original equipment cannister type that I will be fitting soon...
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Re: Nasty sound - wot's 'appening?

Post by slotcarone »

Frankoid wrote:What oil filter have you Per? I was only getting 5 psi hot in my FF so I put a washer behind the oil pressure spring in the pump and the pressure went off the dial, the oil filter blew up like a balloon and burst.. :shock: I have now sourced an original equipment cannister type that I will be fitting soon...
I am assuming that you removed that washer from the oil pump!! :)
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Re: Nasty sound - wot's 'appening?

Post by Frankoid »

Yes!! :lol:
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