Tappety noises and variable oil pressure

[dunks]

Hello there-

I've had my 450 1999 Chimaera for six weeks or so and am totally smitten, but have encountered worrisome problem...

The engine has been sounding tappety on the last couple of runs. It gets worse if you push it. Also, the oil pressure has started fluctuting: it normally runs at about 35/40, but this evening plunged to 15, then came back, then fell again.

There is plenty of oil in the engine, and the warning light doesn't come on.

I'm not much of a mechanic I'm afraid, but if anyone can point me in the right direction it might help smooth my fevered brow.

Thanks-

Duncs

[slideways]

first step clean the pressure sender conection and wiring throughly and make sure its not coroded,also does your pressure light actually work? i had the same fluctuating oil pressure guage this cured mine after buying 2 pressure senders.
check that the tappetty noise isnt a blown gasket
Rich

[davetherave1970]

slideways said:

first step clean the pressure sender conection and wiring throughly and make sure its not coroded,also does your pressure light actually work? i had the same fluctuating oil pressure guage this cured mine after buying 2 pressure senders.
check that the tappetty noise isnt a blown gasket
Rich

My money is on cleaning the sender connections and a blown manifold gasket.

[dunks]

Thanks for the feedback – much appreciated and it’s great to share your troubles.

I’ll check the sender connection first, but it won’t explain the tappety noises - which is where the blown manifold gasket possibility comes in.

From reading various threads I’ve come across six different possibilities:

1. The sender issue – but wouldn’t explain the tappety noises

2. The exhaust manifold – but wouldn’t explain the variable oil pressure readings

3. A fan belt issue – if it had picked up a small stone, apparently it would make tappety-like noises as it wizzed around. The fan belt was replaced last week, so maybe there is an issue there – is the oil pump driven by the serp belt, and if there was a fitting issue, might it cause the oil pressure fluctuations?

4. It would seem reasonable to suppose the tappety noises and the fluctuating oil pressure are linked – which I assume means it’s an oil supply problem. The sump was recently re-sealed with silicone gasket, so maybe this has got into the oil uptake pipe in the sump?

5. The oil pump could be knackered- but I’ve read they’re pretty indestructible.

6. The dreaded c…….. word, which I don’t want to utter because of the expense – but if the cam was worn, would it explain the fluctuating oil pressure?

Any insights into any of these? BTW, the car’s done 38,000 miles and has been much loved.

Duncs

[dogbucket]

dunks said:

4. It would seem reasonable to suppose the tappety noises and the fluctuating oil pressure are linked – which I assume means it’s an oil supply problem. The sump was recently re-sealed with silicone gasket, so maybe this has got into the oil uptake pipe in the sump?
Duncs

I was thinking check the oil pickup. iirc someone on here replaced the cam and everything only to then find the pickup was loose and was causing low oil pressure so the lifters were not pumping up properly.

edit : here

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Edited by dogbucket on Wednesday 7th May 10:08

[StreetDragster]

dunks said:

5. The oil pump could be knackered- but I’ve read they’re pretty indestructible.

Any insights into any of these? BTW, the car’s done 38,000 miles and has been much loved.

Duncs

I can give my insight into this one, indeed oil pumps do seem reliable on our cars, but my car (Serp 450) had very similar symptoms to yours, without the attached tapping noise and a new oil pump cured the problem.

Thanks

Matt

[WazzaL]

As for the tapping, mine is being checked out for this exact thing.

Grab yourself a piece of pipe and with the engine running, place it at each join of the mainfold gasket and where the 4 pipes become one. If it is this, you'll here a hissing noise through the pipe.

If you onl;y get the noise after you have pushed the car through the rev range, then it could possibly be a hydraulic lifter and/or potentially the cam.

If it is a heavier/deeper noise which tends to be through the mid range than it could
meet a a little more sinister - But apparently this is very rare, so no need to worry unduely about it.

- Just information I've gleened from people far more experienced than myself. So hoping my understanding is correct.

[dunks]

Hey slideways, davetherave1970, dogbucket, StreetDragster and WazzaL-

Thanx for your input - I really appreciate it and it is really helpful in my discussions with the garage - the car's going in tomorrow for a deep probe.

I'll let you know the results of the doctor's rubber glove. Fingers crossed it's not the dreaded C-----t word, which would be a challenge as I had to push the money envelope as it is.

Onwards,

duncs

[dunks]

Latest update:

It isn't the oil uptake pipe in the sump
It isn't a sticking oil pressure release valve
It isn't the tappets or shells
It is, however, looking like an exhaust manifold gasket issue, combined with a dodgy sender: as Slideways and DavetheRave thought.

Thanks for the help. STILL not got it back tho'....hopefully tomorrow will see me reunited.

[slideways]

good news
Rich

[davetherave1970]

That's given me a nice warm glow inside
Glad we were right - in many ways!