Loss of power and knocking/popping sound

[ChrisG]

Hi,

Can anyone help?

Just recently, noticed loss of power on engine
OK on straights but definately less power going up hills and accelarating away.

Also sounds like occasional popping/knocking coming from engine.

Was scheduled to do an oil change plus spark plugs this week anyway.
Could anyone recommend oil/spark plugs best to use on 1.9 water cooled 1985?

Anyway, any ideas on problem, let me know.

Chris G

[kevtherev]

popping on the overrun indicates a weak mixture due to air leaking into the inlet manifold.

check
all the vacuum line connections are not leaking, replace split and perished rubber
carb gaskets
Brake servo hose (from inlet manifold) is perished and porous.

But get those plugs and leads changed first.. basics

[Ian Hulley]

Mineral 15/40 petrol engine oil NEVER semi/fully synthetic.
Plugs ... https://club8090.co.uk/wiki/Pe ... plug_types
Change oil, spark plugs,HT leads,dissy cap,rotor arm,air/fuel and oil filters (insist on a Mann oil filter). once this is all done see how the performance is.

Ian.

[dazzzer1]

a quick squirt with brake cleaner or similar around the suspected leaking areas will give you an indication, do it when the engine is running, revs will go up when you find the leak. dont go mad though it is flamable

[moggymorgan]

loss of power knockin and poppin.
think i have all of those but put it down to
newky brown
sprouts
trifle
too much good spirit
will try bread and water and brisk walk on the beach in the morning.will let you know if it works.

[ChrisG]

Hi,
Thanks for the replies.

Replaced spark plugs and oil
Checked spark plugs when took them out, all but one were brown/tan (ie good condition of engine), however one is black/soot deposit.
Could it be a sticking valve that is making the noise.

Put some redex in and gave it a good run but still struggling on power.
Otherwise starts straight away, running idle is good, no difference, just pulling away/accelarating...

Will book it in with local VW camper guy, I've done all I can do.

Cheers
Chris

[Ian Hulley]

Cap, leads and arm ?

[kevtherev]

why immediately suspect the worst?

try the easy stuff first

[..lee..]

compression test it before you throw anymore guesswork at it. does sound like valve. hope i`m very wrong.