Problem with compression

We have a lightweight 1974 2.25petrol engine landy. We have lined up all the timing marks,checked the tappet clearance but it still wont start & sounds like theres no compression. can anyone help please.

Does "sounds like no compression" mean it spins very quickly with little apparent resistance?

If it's a 24v with the big military starter then this is normal - mine giggles if the batteries are fresh.

If you put your hand over the exhaust while trying to start it (long arms or a helper required) can you feel air being pushed out?

If so does your hand smell of petrol afterwards?

If not check you've got the tap set to the tank with the fuel in, then that there's fuel reaching the carb.

Was this engine a runner before setting the timing? If it's got piston rings and valves fitted I can't think how you'd be able to get no compression on all cylinders at the same time (if it was only two it could be no drive to the cam).

phlebas said:

I can't think how you'd be able to get no compression on all cylinders at the same time (if it was only two it could be no drive to the cam).

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loose plugs .......

Thanks guys. Firstly phlebas...yes,it did run before but had to change the camshaft as the old one was shattered around the key,too much play. Sounded like a diesel so took engine apart & fitted a new camshaft,new gaskets & new key. Its a 12V not a 24 as it was modified by the previous owner for off roading. The manual we have is i think, the original (old) and is very vague.The cam wheel has no marks,the crank does,think we have the distributor drive gear in the right position but not 100% sure. Now it just wont start at all.
Sean.. the plugs are ok as are the valve spaces.

Any ideas?

Back to basics i recon, Have you checked that you are getting a spark? hold one of the leads next to the block and check(carefull). Is it happening at the correct time? , timing light would be helpfull here. You getting fuel? Not sure how you check that, but possibly try start it for a bit, then take a plug out and smell ??? If your really not getting compression, the rings couldnt do that on there own i imagine, so probably have your valves opening at the completely wrong time? so maybe check that on the compression stroke of no1 cylinder that the valves are indeed closed... good luck

I have had to look at cam timing on my 2.25 (yet), but in general the cam turns once for each two turns of the crank. I assume the 2.25 isn't unusual.

If it's set up one turn of the crank out the timing marks will look right, but it will open the exhaust valves instead of the inlets and vice versa, sucking air from the the exhaust and blowing it back out the inlet when it is turned over.

This could well sound very odd - perhaps like no compression.

I'd start by checking that - it's easy crank the engine with the throttle open, does it blow air out through the carb instead of sucking, or not puff out the exhaust on cranking.

Then confirm fuel is getting into the cylinders - i.e. the exhaust smells petrolish after cranking should be good enough - as the carb worked before and hasn't been tinkered with.

If that's right then look into the ignition. If it's 12v it should have a normal distributor rather than the copper octopus that lives on the side of my engine. There's plenty of tolerance in the timing - mine runs a bit over about 45 degrees of adjustment, I assume the 12v is similar.

Thanks again Phlebas & you too Kelly, we'll have a look at what you've both said & let you know the outcome x

Hi guys & well we've tried just about everything but just can't get it started so i think its gonna have to go to the garage but thanks again for all your help it was much appreciated & worth a try x

To check the valve timing the crankshaft should be at TDC on no.1 (use timing marks on the pully) The camshaft sprocket should have a P mark which lines up with the first threaded hole anticlockwise of vertical (up). Not sure if it's possible but if there's no timing mark on the camshaft cog could it be inside out?

Did you get a spark then? Did you get fuel?

Hi guys, Oxides...The cam hasnt got a P on it just 3 key slots & is definately not inside out. We're gonna give the info from Phlebas one more try so fingers crossed. Since we've tried all yr suggestions it has tried to start whereas before it wasnt doing anything at all. Will let you all know what happens & thanks very much again for all yr help. x

Hi Guys...guess what... yep shes running again so thankyou so very much for all your help it really is very much appreciated x