oil filler suction.

[gas mart 1]

Hi All, can anyone advise on the following., I have at last found time to get our engine started, its a 4.6 that's not been run for several years. It fired up no problem and has good oil pressure, However after start up I am getting a dull knocking which appears to come from the top front of the engine, on removal of the oil filler whilst running I noticed quite a bit of suction at the filler hole, and after the cap was removed for a minute or so the knocking noise eventually goes and the idle speed also dropped to around 1000rpm.The plenum also appears to get hot quickly ,any advice would be most welcome. Also , what should the oil capacity be for this engine I have put in the best part of 7 litres, and still the oil is at the low mark on the dipstick. I am reluctant to add more as 7 litres seems a lot.
Cheers
martin

[adam quantrill]

Have you got an oil cooler? that can add a litre easily, and a new filter soaks up half a litre. Below the low mark is around 4.5l when dropping the oil out. It's almost 2l between low and high.

In the case of your filler suction, that sounds like a good thing (the crankcase scavenging is working OK). Are you running carbs or EFI?

is there a pinhole under a "mushroom" style breather on one of the rocker covers? If so stick a pin through the little hole under the filter to check it's allowing a little air in.

[gas mart 1]

Thanks for the reply Adam. There is no oil cooler fitted, and its EFI . The system was completely dry of oil before refilling, I do have the mushroom type breather on the rocker cover,, I will have a go at it with a pin , I had to remove the small piece of foam (filter) due to it turning to dust, so maybe this is blocking the breather.

[TVRleigh_BBWR]

if the engine was dry, and sat for a long time some of the lifters may have pumped down, and would be noisy until they pumped back up with oil pressure. or does the knocking come back, on cold startup.

[mrzigazaga]

Is the flame trap clean?

[The Hatter]

You should see suction when you take off the filler cap, it'll be at roughly inlet manifold vacuum (less the effect of the mushroom pinhole). Idle will be raised if you remove the filler cap as you'll be letting air past the throttle plate.

Removing the filler cap is probably unrelated to the change in the dull knocking noise, I would guess it's the engine speed change which affects the knocking noise.

[HOTTY]

hi martin

whats your car type ? (a 400 will have a remote oil cooler if base on)

have you had the engine running for some time, check the spark plugs if one's sooted, your dull noise could be a worn cam but you only need to rush to change if performance is your bag.

hotty

[gas mart 1]

Many thanks for the replies, I got around to having another look yesterday, checked the pinhole in the breather , and washed the flame trap, this had no affect, I have now removed all the plugs, these all look ok , and they all look alike, I will try to pick up some new ones today.

[gruffalo]

What EFI system do you have, is it the GEMS system off a P38 Range Rover and does the engine have the Top Hat liners?

[gas mart 1]

I know very little about the engine other than its a V8 Developments 4.6 cross bolted, I called V8 D but all records for the engine were lost when there system was hacked. It has a Tornado Chip and Ecu set up by Mark Adams. cheers Martin

[gruffalo]

Doesn't look like a Gems EFI system, you have a distributor.

My concern is that it is a liner sliding slightly when cold. I have a Range Rover P38 with a 4.6 and it did just this, knocked when cold, 80k miles later it slipped further and a new engine was fitted.

Just a concern as I said.

[mrzigazaga]

Hi mate....Just did a quick search on engine noises.....
Without a sound bite its hard to diagnose...Are any of these touching on it?

Connecting Rod Noise

If you hear a light knocking or pounding sound, the noise can usually be traced back to your connecting rods. This sound is often most noticeable when the engine is at an even rpm–not accelerating or decelerating–and is often caused by a worn bearing or crankpin, misaligned connecting rod, or lack of oil.

You can single out the faulty connecting rod by performing a cylinder-balance test. This test basically shorts out the spark plugs one cylinder at a time with the engine running. Eventually, you’ll zero in on the ailing connecting rod because the noise will be reduced when its home cylinder is not delivering power.

Piston Pin Noise

Although similar to valve train noise, piston pin noise often has a unique, metallic-sounding double knock and is sometimes most noticeable during idle with the spark advanced. This noise is often caused by a worn or loose piston pin, worn bushing, or lack of oil.

As with connecting rod noise, you can find the offending components by performing the cylinder-balance test outlined above.

Piston Ring Noise

Piston ring noise is also similar to the valve and tappet noise above; however, it is most noticeable during acceleration. Most often, this noise is caused by low ring tension, broken or worn piston rings, or worn cylinder walls.

To troubleshoot each cylinder, remove the spark plugs and add a tablespoon of engine oil to each cylinder. Then, crank the engine for several revolutions to work the oil down past the rings. You can then install the spark plugs and start the engine. If the noise is reduced, the rings are probably the root of the problem.

Piston Slap

A hollow, muffled, almost bell-like sound is usually piston slap. This condition is caused by a piston rocking back and forth within its cylinder. Continuous piston slap means the engine needs service; however, if you only notice this sound when the engine is cold, it is likely not serious.

A continuous piston slap sound is usually caused by worn pistons, excessive piston-to-wall clearance, misaligned connecting rods, worn cylinder walls, or inadequate oil.

Crankshaft Knock

A heavy, yet dull metallic knock is typically crankshaft knock. Loudest when the engine is under load or acceleration, crankshaft knock can be diagnosed by paying close attention to the specific type of knock:

A regular, rumble-like knock is often from worn main bearings.
A more distinct knock is routinely attributed to worn rod bearings.
A sharp, irregular knock can be from a worn crankshaft thrust bearing.


Hope its nothing serious...

[gas mart 1]

I have in the last couple of weeks, Found some time to spend on the wedge, as previously mentioned I have a knocking noise in the engine, which I was unable to trace. So last week I invested in a bigger trolley jack and raised her up as high as I could, with stands etc in place I started her up and crawled under. Bingo!!!, Something in the sump was trying to escape , at the shallow end, by pushing on the bottom of the sump I could change the tone of the knocking, So off came the clutch slave, which was weeping fluid, and then out with the oil and off with the sump. I have taken a look at the crank , all ok there. The engine had spent many years out of the car sat on its sump, so I presume the sump has gone out of shape, any suggestions welcome. Looking at the sump from underneath it looks ok with no obvious dents etc.
Cheers
martin

[TVRleigh_BBWR]

There is a big shinny spot in the middle of the shallow part of the sump, so part of the rotating mass could have been touching, the 4.6 used a slightly different sump with a thick rubber gasket, but I think seeing as you have a dissy setup they would have put an older style sump, and if they was fitting just with sealant, (normally the best idea as the cork ones leak) it may not have enough clearance. you could try and get a rubber gasket for the size of sump your using or add a dent to the sump where it's touching.

you could see if you have clearance buy adding some corrugated cardboard from a box, and put it in the sump, bolt it up and turn over by hand, and see if it's left an imprint. there should be enough oil to be able to turn a single rev without any damage.

[gas mart 1]

Thanks for the reply, as said the shiny mark is where its been touching, i think maybe a couple more runs and it would have been through, the gasket removed was cork I think i will try the dent method first.

[adam quantrill]

If it's just that little bit that's touching you could whack a dent into the sump just in that spot with a lump hammer.

It might be better to get a blowtorch on it first to get the metal a dull red - it will be softer. It looks like you only need around 5mm more clearance in that spot. Give it a paint afterwards on the outside.