Oh dear, lil alfa engine not showing good signs

[jamieandthemagic]

71 gt 1300junior

Today took the car out for 10miles, struggled to tick over sounding distinctly like it was running on 3. And quite rattley / tappetty.

Temp ok
Normal oil pressure.
No mayo in rad
No petrol smell in fresh oil.

So took the plugs out this evening. Looked ok, so measured the gaps. 0.8mm on all except piston 4 which was one 0.4mm.

Took a look inside the plug hole, nothing obvious.

Did a compression test;
Piston 1 - 90psi
Piston 2 - 140psi
Piston 3 - 65psi
Piston 4 - nothing.

I'm guessing its head issue. If it was just 4, I'd suspect a fault on a valve. But maybe the 1 & 3 readings were as a resulted of poor valve seating or something else.

Off on hols this week, so I'll probably take the cam cover off tomorrow, and maybe the head next week.

Opinions welcome

[iva cosworth]

When did you last drive it ?

Might be a sticking valve but not sure how you would unstick it.

[jamieandthemagic]

It gets driven regularly in the summer, every weekend, so it was last weekend.

Don't think it's a sticking valve, as I can see both valves on 4 change their positions after a turn over.

Guess I'm going to have to carry out a leakdown test.

Edited by jamieandthemagic on Saturday 21st June 23:37

[velocemitch]

Ouch that doesn't sound good does it.
Not sure if the top of the Piston can contact the plug and hole it on these Motors, but that would be my (layman's) worry!.

Now's your excuse to drop a 2 Litre in it though.....

[digger the goat]

Swap it out for the V6 lump !!

[fushion julz]

In the past I 've had quite a few of the 1.8 and 2.0 versions of this engine...They have a propensity for chipping/breaking valves...especially exhaust valves. Engine usually runs OK, but on 3 cylinders and with a tappetty chuffing accentuated with the airbox removed