Knocking/rattling engine noise

[sean75]

Hello all,

I decided to get my 75 back on the road after a 5 year lay up in the garage. During this time I have occasionally run the engine and a/c without any issues. When I drove down to the garage to have the work done , coolant replaced brakes checked and general service , oil not done on this occasion as last done 2019 and has only done 500miles since, the engine was as usual whisper quiet. The car was with the garage a week and tested on Monday and passed. the only issues were a sticking brake caliper with a seized bleed nipple( replaced) .

Picked car up on Tuesday and was asked if I noticed had noticed it rattling when cold as when it was took for the test this was evident, I had not had any problem like this since before 2010 and this was solved when the belts and water pump were changed. I started up and sure enough the engine sound like a bag of nails, totally different to what it was like a week previously. The garage reckons its the variable intake manifold so I had a listen when I got home and it certainly didn't sound like the noise I've heard on other intake manifolds that have ceased normal operation.

I took the car back yesterday and explained that the noise had not gone away and sounded like it was coming from belt side.

Having phoned this morning he now says that it'll need more investigation , starting with belt and associated tensioners , idlers, other pulleys and possibly the engine internals.

Seems I'm looking at the possibility of a big problem.

I'll keep you posted and fingers ( and everything crossable) crossed.

BW

Sean

[SD1too]

Originally Posted by sean75

... he now says that it'll need more investigation , starting with belt and associated tensioners , idlers, other pulleys and possibly the engine internals.
Seems I'm looking at the possibility of a big problem.

Don't dive in to the swirling waters of doom and gloom just yet Sean!

As your garage says, the tensioner and possibly the idler wheel for the ancillary belt are the initial suspects for temporary rattling after a cold start (I've had this). I very much doubt that there's anything wrong with your engine internals or that it will be a big problem.

Do keep us informed of what is discovered.

Simon

[sean75]

Thanks for your optimistic reply Simon!

I would like to keep the car ,preferably in running order, but it's very much a secondary or even tertiary vehicle these days as can be seen from my previous post. All depends on what repairs are deemed necessary, I was and still am of the opinion that the belts etc are the issue and not the variable intake manifold, simply due to the nature of the noise and the speed of onset given there were no previous symptoms, there were also no problems evident on the T4 associated with the vis motors etc.

I am however, not a mechanic and therefore don't have the knowledge to diagnose the problem.

Hoping for the best

Sean

[stocktake]

Sounds very much like the belt tensioner. If the belts were last changed in 2010 then they are way overdue according to service schedule. I wouldn't be driving / starting the car unless absolutely necessary until they are checked.

[sean75]

Although the belts were last done in 2010 along with the tensioner, idler and water pump, the car had only done approximately 3000 miles in the period between then and now. It’s possible or more likely probable that the tensioner and or idler is at fault and also the water pump. Either way the belts will be changed next week along with all the other items that are driven by them. The reason I returned with the problem was because I know that it could end in engine death if it was to affect the timing .

I spoke again with my mechanic and he still has a (less convinced) theory that the inlet manifold is the issue , however we discussed the absence of T4 error codes, and the rapidity of the onset of the noise. He also agreed about the location and bearing type noise rather than clicking plastic at the top of the engine.
We’ll see what next week brings.

[stocktake]

Belts, pump, tensioner and idler are out of service time of 6yr by some margin.

To check inlet manifold is simple:

Remove power vis (the one on the top) it's a simple electrical plug and four screws and off it comes.
Look into the hole it came out of and you will see a brown arm with a slot in it, this arm should move side to side and be free but firm in movement.

Any up and down movement other than flexing of the arm is wear. For the butterflies to be making such a racket the arm would have to be detached from the butterflies to allow them to be swinging and rattling about, it would be very evident on this test if this was the case. Do not start the engine whilst carrying out this check.
Costs nothing to check for this fault .

[SD1too]

Originally Posted by sean75

... the car had only done approximately 3000 miles in the period between then and now. It’s possible or more likely probable that the tensioner and or idler is at fault and also the water pump.

I'd say that it's virtually inconceivable that a properly fitted tensioner, idler wheel or water pump would fail after as little as 3,000 miles. Timing belts attract fear and irrational diagnoses. There's going to be zero wear after 3,000 miles irrespective of the number of years that has elapsed. Mine were in immaculate condition after 90,000 miles and 18 years! Think carefully about that evidence.

Originally Posted by sean75

I spoke again with my mechanic and he still has a (less convinced) theory that the inlet manifold is the issue , however we discussed the absence of T4 error codes, and the rapidity of the onset of the noise.

I have heard manifold chamber rattle. It is continuous, loud and very alarming. The noise is the result of a worn valve linkage so if the actuator is o.k. you wouldn't expect a fault code on T4.
Why do you think that a rapid onset of the noise points to belts rather than anything else?

Simon