Oil cooler whine. Plumbing direction?

I need to get this issue fixed because the wife is starting to moan about it!

The problem is, my oil cooler (89 328) makes a loud whine (its definitely that not the wife ). This is amplified by the air intake which pipes it into her left ear. (note RHD car).

This issue has been mentioned many times on here (including by me) but no real conclusions. Some cars only make this sound when cold, some dont make it at all and mine does it all the time, and loud.

I just realised that my oil cooler is plumbed in reverse to the way the parts book diagram and WSM shows it. So I thought that was the cause but when I phoned another UK 89 328 owner his is the same. But maybe it still might be a factor.
On mine, the hose from the base of the oil filter goes to the BOTTOM of the oil cooler and the hose at the bottom of the rear crankcase goes to the TOP of the cooler.

Is this the same on all cars? Maybe cars which dont make the noise at all have it plumbed in the direction the parts list shows, which the top engine hose to the top of the cooler and the bottom hose to the bottom, which does seem logical. This also makes more sense because the flow direction would then mean oil enters the cooler at the bottom instead of the top.

Maybe I should try swapping the hoses over, if they will fit. One of the posts on this forum does mention reversing the oil cooler flow stops the noise.

 

Mines an 88.5 version and its plumbed the opposite way to yours. I don't get any whining except when the engine is very cold ( air temp below 5°c on start up). I haven't really attributed this to the oil circuit, more like aux belts. What sort of oil are you using?

 

Thats interesting..

Its AGIP HTS Synthetic 5-40 from Superformance. But it did the same on other oil.

 

Andy , that's weird. Hoses on mine are top hose to the oil filter, bottom hose to the block...

 

Right, I am going to swap them over.

But, the parts list shows the bottom hose as having a 90 deg elbow on the cooler end. Neither of my hoses have an elbow at the end. I am not sure if they will fit the other way but I will have a closer look.
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That's correct, it does have an elbow on it. Suggest either maybe you have US spec hoses (the US cooler is in a different place) or some kind of rebuilt version

Superformance sell UK spec replacements...

Engine (General) Parts for Ferrari 328 - Superformance

The bottom one is a bit of a pig to get on though.

Also, be careful with the cooler, when I replaced mine I had to cut the old ones off - metal-metal corrosion - Steel hose end, aluminium cooler.

 

But Marks (Markrw) car is plumbed the same as mine. I guess I will be looking at everyones 328 oil cooler hoses at the Horsham event on Friday!

 

Odd, maybe we have come across a minor "model variation" caused by a shortage in one of Luigi's parts bins??!

Suggest have a chat with the guys at QV and/or Autofficina & see what they know.

The lower hose on mine goes through a very tight bend after the fixed elbow & it only just clears the bell housing. Maybe they redesigned it? My chassis # is 79393, is yours before or after that?

 

81321.
Marks is a late car as well. Could be a design change, the way it is plumbed there are no tight bends or clearance issues so maybe thats the reason.

 

The way yous is plumbed should mean the cooler stays full of oil after stopping, which I suppose has to be an advantage, except of course it wont naturally drain out during an oil change.

 

Not sure of the complete layout for the oil cooler, but oil feeding from the oil pump to the bottom of the cooler with the cooled oil going to the sump should keep the cooler nearly full of oil. But some oil could drain out letting some air build up in the cooler.

The cooler should discharge the air IF the highest point is the discharge side after oil flow. Air could cause cavitation, which could sound like what your wife is reporting. If there is access while running a screw driver or mechanics stethoscope can be used to pinpoint where the sound is coming from either in the cooler itself, piping, or the oil pump filter etc.

If it is air trapped in the cooler unmounting it and rotating while running to push the air out should make the noise go away. If it does not help then a restriction maybe causing the noise.

The noise may also be travelling from somewhere else ie following the cavity that the oil lines and cooler are in....

 

The way mine is plumbed, the discharge is at the bottom. So yes, it could be trapped air causing cavitation. A stethoscope shows it is the cooler causing it and more specifically the bottom of it, where the discharge is.

 

Maybe Ferrari realised the NRV flap in the oil filter didn't hold the oil cooler full for very long after stopping so they changed the pipes over without contemplating the issue you have. You very rarely see heat exchangers like these configured with the outlet at the bottom for the very reason mentioned. Did earlier 328's have a reputation for running bearings more quickly due to frequent starting with oil starvation?
On yours can you see the oil pressure pulsing when warm?
This point also makes it more clear that checking the oil level after 15 mins of stopping whilst hot will give a more consistent reading than measuring it cold, regardless of how the oil cooler is piped.
Just a theory!

 

My guess would be that air bubbles will tend to float in the cores at the discharge side of the cores with the oil flow bypassing those cores. The only way to get them out is to make the air go to the top and replace it with air. Probably no air bleed nipple so the only "easy" way is to get the cooler lower than the whole discharge line to the sump.

By rights the oil pump should act as a non return valve for the feed to the cooler. The oil line from the sump would need a high point to stop the air going to the cooler, ie break the siphon effect which gets the air into the cooler. Another option would be a non return valve, but this would need sizing and selection carefully so it did not add a risk of failure.

I would suggest purging the air first and see what happens, may only be an issue when the cooler is drained (ie hose replacement) and not purged of air properly.

 

The noise is quite common in cooler temps and seems to simply be a function of the colder oil/friction internally. My '89 328 did it regularly at temps of 50F and below for the first couple of minutes after cold start-up using 20W50 installed at a local Ferrari/exotic shop at the car's first oil change after I purchased it. It has never done it at those temps since I switched to Mobil 1 0W40 a couple of years ago.

IMO, I wouldn't worry about the noise at all. OTOH, if it's a big deal to your wife then it IS a BIG DEAL and must be fixed! Try 0W40 before messing with plumbing.

 

The oil coolers do seem to be a source of noise - if you put your hand on the top hose when the engine is running the thing is buzzing like a demented bee! Quite odd.

 

Also check to make sure the cooler is not in contact with some other part. I had a QV years ago that whined loudly and discovered it was just barely touching a chassis member which amplified the buzz.

Dave

 

Thats a good point. The oil cooler is mounted on rubber bushes but the cowling which the air hose is connected to is bolted directly to the cooler. So the noise from the cooler transfers to the cowling and then up the hose and out the side intake like an old fashioned gramophone horn!

I might try some other oil but the noise is constant, it is slightly louder when cold but not much, its the loudest sound when driving, louder then the exhaust.

 

A quick inspection of several 328s today revealed the following:

At some point during 89 they reversed the oil cooler hoses.

The ones with reversed hoses make the loud whine, which some owners seem to incorrectly believe to be caused by the gearbox having straight-cut gears (which it does not of course).

Earlier cars with the plumbing according to the documentation do not have the whine.

So there we have it... an undocumented change.