Running rougher & increase in noise......

Rough and noisy running.......

So after a month of running the s/s vintage speed exhaust I have noticed a sudden increase in noise and a rougher sounding engine.

No loss of power or speed BUT you just know your engine and know when it changes.

So took the van off the road and took the wife's car to work this week.

Initial checks

1. Check and tighten ALL exhaust bolts - Suspect a leak in the exhaust. No sign of anything. Some bolts a little loose BUT no leaks that I could see.

2. Run VCDS Log - Hooked up the laptop and took idle logs, results looked fine no DTCs or any obvious changes in readings from all sensors.

3. Cleaned oil / crankcase breather - My engine always suffers from oil / water mayo at the crankcase breather around the oil filler and via breather valve pipes. Cleaned them all out with some WD40 and refitted

4. Tappets - Re-set tappets. 2 valves where a little loose so reset them. None where tight (Tight valves are = bad valve seats or stretched valves)

5. Checked distributor cap and rotor arm - Some mild tarnish / matt colour as they have done quite a few miles. Just cleaned them up as there where no other obvious problems.

After the above still sounded quite loud and sounding rough.

So not cured with the above. Was worried that the engine could be on the way out SO decided to check the worst things so this week I did a compression test & check sparkplugs.

Sparkplugs

So removed all sparkplugs

So here are the four plugs barraged in the cylinder positions.

All plugs showed a good tan colour indicating a correct mixture (was expecting black rich carbon)

Some plugs had a cracked patterned gunk on them. Here is a close up

So this does not look like a running issue or maybe a rich BUT burnt on effect due to high temperatures.

So plan is to replace all plugs with my spare set and clean these up and keep them as a spare.

Compression Test

So once the plugs are removed managed to get my compression gauge installed (quite hard screwing a rubber hose into the sparkplug threaded holes)

Once installed the procedure is to remove Fuse 14 (20A fuel pump and injector fuse relay power) so no fuel.

Dis-connected coil to distributor main HT lead so no spark.

Turn over the engine on starter 5 revolutions with a WOT (Wide Open Throttle) and the gauge will show and hold the peak compression in psi.

So here are the results

1 = 135 psi
2 = 140 psi
3 = 140 psi
4 = 140 psi

So all are high and within 10 psi of each other. So no issues with valve / cylinders etc.

Great engine is in good condition!

So what further issues could it be:

1. Vacuum leak - Suspect there could be a vacuum leak as had a few instances of rough idle. Smoke or pressure test this next.
2. Sparkplug condition - Replacements should confirm this.
3. Exhaust leak - Cannot see one but will do a test to confirm
4. Exhaust internals - Could be just the exhaust baffle working loose or broken inside. my mate Ben had a vintage speed which went wrong and had to get a replacement. Maybe the same BUT hard to prove without anything to replace it with.

So maybe maybe its just me being paranoid. Glad compression tests results where good!

Update to follow.........