Comments on: Ferguson FE35 Compression Test

By: Roger

Roger — Tue, 15 Feb 2011 12:39:34 +0000

Hi All, I have fitted new pistons, liners, valves, injectors, pump ETC. to my 23c and she is now very hard to start and smoking badly, I’m pretty sure the timing is set correctly and I have set the pump timing a dozen time trying different settings with no improvement. The smoke is blue indicating unburned fuel, i’m now runnibg out of ideas and would like to check the compression. All the standard compression testing kits seem to cater for injectors with clamp bolts either side of the injectors, the 23c has the clamp bolts slightly below the injectors and use an L shaped clamp. Does anyone have either an adaptor for this or a compression testing kit I could borrow for the job? I Live near Telford, I could either collect or I will pay the transport cost.
Roger

By: Rich S

Rich S — Wed, 08 Dec 2010 11:41:33 +0000

Hi all,

Very interesting reading. I’m going to compression test a friends MF35 this next weekend as it’s an appaling starter and is using a lot of oil when comp ploughing (pressuring the crankase – heavy breathing through filler and dip stick) so I suspect rings. It’s had a re conditioned head on it about a year ago so this should be pretty good.

I’ll test to the pressures you’ve experienced above although 400+ sounds high. Are the engines above a four cylinder standard or a Perkins version? He has a standard engine so I’d like to know if these pressures are relevant. Many thanks Rich

By: heskencren

heskencren — Mon, 01 Mar 2010 09:25:44 +0000

Are we all measuring the compression in the same way? That is, with our non-return valve in the same place so we trap the same tdc volume as the next guy???? On high CR engines lost volume causes a more significant error.
I have now measured the compression on my tired old 23C. I get 380,440,420,420 psi. Isn’t that something like 28:1 CR? Is this not way above spec?

I have measured this with a Gunson hi-gauge. The threaded bit of the tube that normally goes down a spark plug hole just fits down the injector nozzle counterbore and the o-ring just about goes down too. The plain shank doesn’t but that’s good as it holds the o-ring down. (Ok the couterbore may be a bit rough and the corner may mash the o-ring after a few goes but I get the numbers.) This puts the non-return valve as close to the true volume as possible as the nozzle insertion depth is similar. This was held down with a modified injector clamp. A vee was cut in the pad to allow the hi-gauge hose thru whist keeping the tube perpendicular and a slotted m16 nut used as a spacer under that. The nut may splay open and ride down the plain shank of the tube so improvise further!
****WARNING**** The FSD of the gauge was exceeded so i put one with 600psi FSD intead. Keep volume of adaptors as small as possible to reduce the number of compression strokes required to reach a steady reading.
****ANOTHER WARNING**** If the hardware explodes or pops out then bits may hit you so take precautions.
How is everyone else doing it?
Can we all agree on a standard (pun not intended) compression test method?

SO.. I get bad starting. I also get bad idle smoke and lumpyness. A bit like the “before” 23C on the DVD. Can I rule out bad compression? Rather not remove the head unless i have to.

By: P Comiskey

P Comiskey — Tue, 02 Feb 2010 21:49:21 +0000

Re 4cly 35 possible reason for low compression could be valves seated to low in cly head might need a few inserts fitted?

By: Vintage Tractor Engineer

Vintage Tractor Engineer — Tue, 12 Jan 2010 22:17:23 +0000

Hi Everyone,

More info here, from Dave’s 23C engine.

http://vintagetractorengineer.com/forums/topic.php?id=157

Steve.