Cam Knock/tap

[lemmingzappa 75 1 Cars]

I've been having issues with my 8v engine. It was originally suffering from a pinking issue, 90% of which has disappeared since changing the dizzy for a rebuilt, recurved unit (refurbed by H&H). The engine no longer has pinking issues, until it reaches high rpm (5.5k +) AND high road speed. It doesn't seem to pink at high rpm in the lower gears, but once travelling at speed in 5th gear and reaching 5.5k/6k it seems to want to pink badly before it hits the rev limiter (never touched the limiter in 5th gear on track, due to this issue).

 

Oil is being blown past the dizzy seal and is leaking out of the vacuum advance capsule (this was happening on both the old dizzy and the rebuilt one). I thought this may be due to the breather pipes being blocked and pressure building inside the engine. But after inspecting and cleaning all the pipes out a few weeks go, it still persists. I'm also unsure if this is related to my main problem which I will explain next:

 

1.9 GTi XU 8v
2.0 Big Valve Head (XU10 QEP Flowed)
PT36 Kent Cam
Vernier Pulley
1.6 GTi Flywheel
1.6 BE3 Gearbox
GTi6 Baffled Sump
ProTech 4 Branch Manifold

 

Yesterday when I hit around 5500 - 5700 rpm in 5th gear (doesn't happen very often as most of my journeys are around town), I noticed that the pinking noise returned so I backed off instantly. The noise was then followed by a small cloud of light grey smoke out the back of the car and nasty rattle. There was plenty of oil in the engine at the time and nothing was out of the ordinary.

 

After pulling over I could hear that the engine was knocking, which I initially thought was a bottom end knock, but after speaking with a couple of local non 205 specialists, they seem to think it is coming from the cam area and not as loud as a bottom end knock. Here is a phone video, audio quality is not so accurate on these though so hopefully not too misleading:

 

http://youtu.be/Xsm9CilqwKA

 

The oil/fluid spitting out of the exhaust was something I have only really noticed since topping the engine up with more oil to be extra safe and have been told that could just be happening due to the engine being over-filled now. I've also been told that it could be running rich and my brother also mentioned that it smells of fuel when under load when driving behind.

 

Oil pressure currently seems normal, fluctuating between 25-60 psi depending on the driving conditions.

 

The engine was rebuilt a couple of years ago and hasn't covered much more than 10k since, if I remember correctly. Sorry for the lengthy post, but I want to provide as much info as possible. What sort of thing should I look for if I whipped the cam cover off?

 

Thanks!

Edited June 3, 2013 by lemmingzappa

[DamirGTI 358]

Remove the vacuum hose from the dizzy advance capsule , and then try a spin if it still pinks ..

 

The sound cod be valve clearances (check with a feeler gauges) , worn/dished lifters (surface can be rectified by taking them out and grind the tops with a 600grt. paper lubed with engine oil , resurfacing in spiral motion it'll clear the dish on tops of the lifters) , and might be something rubbing inside cambelt area so check that first .

Also , check if all the valve shims are in place , cos if over reved they tend to spit the valve shim .. rarely , but it's possible .

 

D

[lemmingzappa 75 1 Cars]

Thanks for the advice, you will have to excuse my lack of knowledge

 

Are the shims a flat piece of metal which sit between the top of the valve spring and the bottom of the lobes?

[welshpug 1,721]

Not quite, they sit on top of the valve stem under the bucket.

[Anthony 1,003]

Hmmm, that doesn't sound good

 

The pinking at top end doesn't sound right as it certainly didn't used to do that on the original 1.9 distributor, nor on the 1.6 before it failed. I wonder if the modified advance curve either isn't correct or you've got it setup wrong, meaning that it's too far advanced at top end. A normal dizzy tends to pink between 2000-3000 when excessively advanced, but a recurved unit might be different.

 

Either way, my plan of attack would be as follows:

 

1. Do a compression test to ensure everything is healthy in terms of rings, HG, valves etc
   
2. Whip the cam cover off and double check the lobes all look in good condition and none are excessively worn
   
3. Check the valve clearances - I can't remember the exact specs (it will be on the Kent website) but they should be in the ballpark of 0.15-0.2mm inlet and 0.35-0.4mm exhaust

 

Good luck!

[cheesegrater 43 1 Cars]

Hmmm, that doesn't sound good

 

The pinking at top end doesn't sound right as it certainly didn't used to do that on the original 1.9 distributor, nor on the 1.6 before it failed. I wonder if the modified advance curve either isn't correct or you've got it setup wrong, meaning that it's too far advanced at top end. A normal dizzy tends to pink between 2000-3000 when excessively advanced, but a recurved unit might be different.

 

Either way, my plan of attack would be as follows:

 

 

• Do a compression test to ensure everything is healthy in terms of rings, HG, valves etc

   

   

• Whip the cam cover off and double check the lobes all look in good condition and none are excessively worn

   

   

• Check the valve clearances - I can't remember the exact specs (it will be on the Kent website) but they should be in the ballpark of 0.15-0.2mm inlet and 0.35-0.4mm exhaust

 

 

Good luck!

I have a compression tester at Kam if you want to borrow it Josh.

[lemmingzappa 75 1 Cars]

it certainly didn't used to do that on the original 1.9 distributor, nor on the 1.6 before it failed.

 

I can't imagine it happened on the original dizzy, but I did also have the pinking at top end on the 1.6 dizzy when flying down the main straight at the ring.

​

 

Here are my results from today's testing, going from left - right on the cylinders when facing the front of the car:

 

Compression Test

 

Cylinder 1 - 115

Cylinder 2 - 205

Cylinder 3 - 210

Cylinder 4 - 205

 

I then proceeded to drop some oil down the spark plug hole and run another compression test on cylinder 1. The pressure then jumped up to 200. I have been told this could be a suspected piston ring failure. There is no out of the ordinary smoke from the exhaust, just the horrible tapping/knocking.

 

After checking under the cam cover, I couldn't see anything wrong. All the followers looked to be in the right place and I couldn't see any excessive wear to any parts.

 

All of the inlet/exhaust valve clearances are correct (checking against the measurements on the Kent website).

 

Everyone I've spoken to about this reckons it's most likely a piston ring failure, but the knocking noise does not seem to add up with that symptom?

[welshpug 1,721]

just listened to the video, a very difficult one, certainly doesn't sound right at all, almost but not quite a manifold tap, which is so common with these manifolds, welded a few up!

 

 

but that doesn't address the compression issue, and its not a "knock" as I would imagine a knock to be.

[lemmingzappa 75 1 Cars]

I had a good look around the 4-branch and couldn't feel any leaks, I would say it's more aggressive sounding in the flesh than any manifold leak I've heard in the past.

[PhilNW 66]

Number of thoughts, Have you overfilled the oil, try taking spark plug out to check condition of no 1 cylinder, very low pressure compared with others, damaged valve, overfuelling washing oil off cylinder wall, try running with plug then injector disconnected

[calvinhorse 870]

The pinking could have melted a valve or piston in cylinder 1.

 

Piston or ring damage would explain oil getting blown out as the engine would have excess air pressure in the crankcase

[lemmingzappa 75 1 Cars]

Have you overfilled the oil

It wasn't overfilled at the time of pinking, but it was overfilled afterwards as I wanted to be sure it wasn't going to run dry and was too hot to check the levels properly on the motorway.

try running with plug then injector disconnected

So I should try running it with just plug 1 removed and then also try running it with plug 1 and injector 1 removed? What would this tell me and what am I looking out for?

[DamirGTI 358]

So I should try running it with just plug 1 removed and then also try running it with plug 1 and injector 1 removed? What would this tell me and what am I looking out for?

 

You're looking for engine "power balance" , when you unplug either the ignition lead or the injector with the engine running , there must be consistency on all the cylinders .. say if you unplug the ignition lead (same goes for unplugging the injectors ..) and move it off the spark plug and the engine doesn't start to shake/loosing power/revs/runs rough on particular cylinder - you found the bad one ..

 

So when unplugging injector/ignition leads , cylinder by cylinder , the healthy engine must perform as described above - shake/loosing power/revs/runs rough , and when you connect all back it smooths up - that's a good one .

 

If unplugging ignition lead/injector , and on any of the 4 cylinders this doesn't have any effect on the engine running wise then that's an problem .

 

 

The best way to detecting possible engine internal mechanical malfunction/health is - a leak down test .

 

 

D

Edited June 4, 2013 by DamirGTI

[lemmingzappa 75 1 Cars]

Thanks Damir

 

Unable to test the other 3 at the moment, but when removing the lead from Cyl 1 the revs do drop. When re-connecting the lead the revs climb higher (from cold start).

 

I will try and find somebody to run a leak down test for me, not sure how easy that will be though as i'm up against time (daily driver)

[Tom Fenton 1,632]

I wouldn't waste your time with a leak down, it sounds like its breathing hard and well down on compression on one cylinder, clearly there is a mechanical fault of some sort, which is all a leak down test will confirm, you may as well get it in bits to see whats what. From your dry/wet compression test its pointing at rings on that cylinder. You can leave the engine in the car, take head off then drop sump and remove big end cap to get the rod and piston out with the rest in situ.

[lemmingzappa 75 1 Cars]

Thanks Tom, I'm glad it can be done in situ. Now it's time for me to start looking for assistance

 

Regarding the leaning out at top end. Could this be solved by increasing the fuel pressure by using one of those silly FSE boost valves or is it more likely a faulty AFM?

Edited June 4, 2013 by lemmingzappa

[Anthony 1,003]

You need to establish if it is even leaning out before blindly throwing fuel at it.

 

If it is leaning out at sustained high revs/load then it is potentially a failing fuel pump, FPR or similar.

 

First things first, you need to fix the known issue on cylinder 1, and if the top end pinking persists, pull a few degrees ignition advance out first to rule that out.

[lemmingzappa 75 1 Cars]

Time for me to start pulling this apart I think, will I need any specialist tools when removing the head bolts etc..?

Edited August 19, 2013 by lemmingzappa

[Tom Fenton 1,632]

You will need a T-55 torx bit 1/2" drive plus a decent breaker bar for the head bolts. Other than that general tools will suffice.

[lemmingzappa 75 1 Cars]

Thanks mate, barely pulled any engines apart so this should be interesting for me

[Anthony 1,003]

Before taking it apart, turn the engine so that the timing pin lines up on the bottom pulley and mark/note the position of the vernier relative to the head (there's no timing hole to pin it) so that you don't end up getting it a tooth or more out when you come to refit the head. Obviously you'll need to double check the cam timing regardless, particularly if you need to get the head skimmed to make it true.

 

When the head is off, fabricate something to clamp the liners in place so that they cannot move, as if you move them and disturb the liner seals, you're potentially in a whole world of pain. Some large diameter washers, some lengths of copper pipe and the original headbolts will suffice. Of course, you may end up having to remove the liner if it's damaged through whatever the failure is that's happened on that cylinder...

 

You'll need a half decent torque wrench when it comes to reassembling the engine too.

[alexcrosse 124]

And a swear jar.

[mike174 9]

Time for me to start pulling this apart I think, will I need any specialist tools when removing the head bolts etc..?

Any news on this yet Josh?

[Syklig 0 1 Cars]

Any progress in finding out what happend to your engine??

[lemmingzappa 75 1 Cars]

Struggling to find the time to even start at the minute >.<