I have a 1979 Austin Sherpa with an "O Series" 1700 petrol engine.

Engine was running great before I replaced exhaust/inlet manifold and an SU Carb. Then it just wouldn't start. The engine was cranked over probably for 20 sessions (with batteries on charge) before I realised that it was the timing belt had somehow completely shifted.

I am familiar with setting the camshaft timing marks when installing a new timing belt so I rotated the camshaft pulley wheel to where it should be and saw that the crank pulley wheel had rotated around 180`(that's a lot of slippage) I remember when I first started to crank the engine there was a heavy pause like what I imagine Hydrolock would feel like. After that it just cranked away but I would say a little slower than it would normally. I currently have a massive cold cranking ability on new batteries so the starter motor would have all the juice it could ever wanted.

It is possible that a bolt or something was dropped down into the belt area. It is also possible that tissue paper was left in the inlet ports when I was cleaning off the manifold gasket which would have got sucked in on 1st crank.

So presuming the worst that tissue paper was trapped between the pistons and the valve tops - Do you think there's a likelyhood of valve damage and what would be the best way to check without a leak down tester?...and would I even notice slight but effective damage to the valves on disembly.

I believe that the engine is an "interference engine" but in my favour the valves travel straight up and down so if there was interference the valve tops would have been square to the piston tops.

  • Welcome to Motor Vehicle Maintenance & Repair! When you were checking the cam timing, which "timing disc" was 180deg out? Are you talking about the cam gear? Commented Jan 13, 2018 at 2:41
  • There seems to be something missing here - if the only work was done on the manifolds / carb, what was done on the timing belt as it should not slip unless a bolt or nut was dropped into it to cause a blockage etc.
    – Solar Mike
    Commented Jan 13, 2018 at 9:04
  • If you are talking about the timing of the cam, realize the cam spins one revolution per two revs of the crankshaft. If the crank was on TDC and the cam was 180 out, this is perfectly normal. The crankshaft will pass top dead center twice as it goes through the four cycles while the cam will only pass its timing mark once. Commented Jan 13, 2018 at 9:15
  • Wow! - I woke to 3 relevant comments this morning. Thankyou. Commented Jan 13, 2018 at 10:23
  • Wow! - I woke to 3 relevant comments this morning. Thankyou. Sorry if I hadn't been clear- But suffice to say that the crankshaft pulley had rotated 1/2 a turn in relation to the camshaft pulley (I guess that's 90` of the cycle). Yes solar Mike - I had missed something re. the tissue paper. I have since edited my post. Thanks again all. Commented Jan 13, 2018 at 10:32


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