Turning over engine by hand...hitting a tough spot...??

[sirivor70]

Hi there folks. Wondering if a more mechanically minded person than I can shed some light and tell me if I have an issue or not.

Am prepping a 1.9AAZ diesel to go into my van as a replacement. Its out of a crashed 95 Vento, 50k on the clock and I saw the engine running before I bought it. No problems there but has been sitting idle for 3 years now.

Currently have it on an engine stand and putting all the bits and pieces from the 1.6TD JX onto it...sump, engine brackets etc. It does not have any oil in it just yet and neither does it have the fly wheel on, but everything else is present and accounted for.

Last night I had my mechanic friend over to change the timing belt as its something I would not feel comfortable doing on my own. No problem there but after fitting it we started to crank the engine with a rachet and socket on the crank bolt (pulley is off the crank) just to see everything was a ok.

Turns lovely until you come to the fourth revolution and then it get noticably harder to turn on that revolution. It still turns over but requires extra effort... no metal on metal sounds or anything but struck us as a bit strange. We took off the rocker cover to see if anything might shed some light on this.

The only thing we saw was that on the hard revolution, it coincided with the depressing of the inlet valve by the Cam shaft on the cylinder nearest the timing belt (don't know if that is cylinder 1 or 4?). As the cam turns to depress the (and dont know the exact name of this) silver "piston" above the spring its get harder and imediately finds relief as it lets it back up.

However we are still none the wiser if we have a problem or not. We honed in on this valve as it coincided perfectly with the revolution, but it being an engine, it might coversely be the up-stroke somewhere else...stuck exhaust valve not opening....only guessing here...obvious I have no idea what I am talking about now..

My inital un-mechanic brained thoughts were that it might be a tougher/harder spring on that valve...could that be the case?

Any thoughts gratefully appreciated as I would like to know now before doing damage when I eventually fire it up.

Many thanks.

[CovKid]

I'm not sure our thoughts will help much as we know no more than you unless its stripped down. Could be lack of lube or rust/corrosion in some area - doubt its an over-strong spring. Will it turn over on a starter motor?

[armyphil]

Personaaly I would take the injectors out and squirt a tiny amount of oil down each cyclinder being as it's been stood for a long time maybe just as covkid said corrosion on the cyclinder bore making it a wee bit harder.

[Plasticman]

How did it feel turning over prior to fitting the new cambelt?
mike

[fullsunian]

It does sound like you have valve/piston contact, i.e the valve timing is out. Have you and your mechanic mate checked the belt to see if its timing up correctly?
Or you could be worrying over nothing, most engines turn over with tight spot, when each piston is coming up on compression. But not only on one turn in every four..
IAN

[humphry]

as armyphil said take out the injectors put a bit of oil down each bore and try turning again that way you're not pushing against any compression in the chambers and it should spin freely and check your timing one tooth out on a belt can make a big difference

[dugcati]

Just hope it's not a case of 3 duff cylinders and 1 good one added to a lazy starter/dying battery!

[Bert2]

Hi
i agree with all those above, remove the injectors and squirt each cylinder with a drop of oil, if when turning over by hand its still stiff then there is something amiss when it goes still have a look what the valve gear is doing, at least without any injectors you can rule out compression

[Plasticman]

Which goes back to my point, before changing doing anything, how does it turn/feel compared to before doing the work, because if it was fine prior then no point wasting time oiling bores, recheck the timing etc.
If it was like this prior then yes you have a problem to investigate,
If you didnt check rotation prior to doing the job? then this is just the reason why I wouldnt and havent ever redone the work of previouse budding mechs. and why it is important to know what your doing and understand what your doing when stripping in this instance a motor.
mike

[sirivor70]

Honesty don't know what the rotation was like before we went to change the timing belt. Engine has been on an engine stand for three years now and we just got straight into changing the time belt last Sat night. My mechanic (fully trained main dealer) says the engine has good compression on each cylinder, just that tight spot on one.

All the timing marks line up so I don't believe that we are out there. So my plan of action this weekend is as follows:

> Take back out all four injectors.
> Squirt some oil into the chambers.
> Rotate again and since compression is now ruled out, see if anything gives.
> If still there, recheck timing marks
> If still there....formulate a plan B

Sounds like a plan. She is a sweet engine....don't want to mess this one up as AAZs with 50k on the clock are hard to come by these days.

Thanks for all you help folks.

[silverbullet]

You said that it goes tight when the cam is opening that particular inlet valve. You may well have a bent inlet valve or something in that cylinder (foreign object) that is causing interference. Does it "creak" when you turn it slowly by hand?
If the engine's been on a stand that long, it's not unknown for wildlife to crawl into the confines of a port and then cylinder and be unable to climb back out.
There was a similar thing on Subaruvanagon where a guy's freshly rebuilt EJ22 got wrecked because a mouse had crawled in the crankcase breather and got trapped in the oil system. Dead mouse, wrecked crankshaft.

[sirivor70]

Could very well be. All sorts of creatures in and around garages.

Am going to take this one nice and easy......

[silverbullet]

Can you see anything down the injector port with it removed? If it was a petrol you could whip a plug out and have a look with a small LED torch. You may well have to take the head off, either to find out what's going on or to remove the dead rodent...