No Compression
 

Car broke down last week, engine just died. Breakdown mechanic suggested timing belt but garage has checked and it's ok, timing ok too. That's all they've managed to do so far as they're very busy, but in the meantime I wondered if any of you knowledgeable people might have any ideas. The starter turns the engine but there's no compression, cylinder head complete overhaul very recently. In around fourteen years and 120,000 miles in my ownership (over 240,000 in total) I've never needed to call out rescue (Britannia have done well out of my premiums!) and MoT pass a couple of weeks ago with no advisories and amazingly low emission readings, engine's been running like a dream since head replaced, all very frustrating!

I should have said, car is a 1992 Torslanda.

Very odd Angie, no compression on all cylinders?🤔

Yes, engine just spinning over, very strange.

Can you post a video of turning it over?

Sounds like the bottom cam belt gear has broken the locking tab causing timing to look right but be out

That's a bit extreme.

Timing belt could have slipped? Has the tensioner pulley been tightened and re-tightened properly after the head work?

Timing belt all ok, camshaft is turning apparently, mechanic thinks the 'something' key, sorry can't remember what he called it, might have sheered and caused the timing to have slipped, anyway that's his next investigation before removing cylinder head. I did ask if faulty crank sensor could be a factor and he thought not. I wondered if new, and obviously stronger, valve springs following overhaul could perhaps have caused extra stress. I'm just waiting to hear what the conclusions are but thought others might have experienced a similar problem and found the cause, could save garage time (=money!).

Thanks all of you for going to the trouble of replying.

Not at all extreme and a fairly easy fix

The tab or key on the crank pulley like I said. If you are square tooth then easy enough to replace round not so simple as drop in new ones not available

Being a B200 there is risk valves have bent but you might be lucky

I wonder if the engine in a tors is an interference engine?..Firstly sorry for your troubles...Does sound like the shear key has either gone on crank pulley or camshaft..and since the head has done fairly recently makes me think the cam gear may have come loose..If this happened to me i would either remove rocker cover and check for operation with a rachet on the crank pulley..(disconnect battery first)..as it has no compression should not be too hard..or i would remove radiator front grille all belts..is alternator..power steering..now you can remove cambelt cover and get a good look and and access to all pulleys from cam to crank..your problem hopefully will become evident..Here"s hoping you"ve had a lucky escape..hj.

Thanks for that. The mechanic has done some investigative work, valves are all moving freely which suggests no bent stems, he still thinks it's the shear key which has either fallen out or broken but they're so busy at the garage it might be a few days more before they can do any more.

My thought has been possible crank sensor failure or even disconnected (could even have happened when head refitted) but the mechanic thought not. Years ago after I collected my Moggie Traveller from the garage after some work (different garage) I discovered it was barely driveable, hardly any power at all. I knew enough to be able to loosen the distributer and advance the timing after which all was well. It seems to me that if, as the mechanic said, the timing is 90 degrees adrift, maybe a failed crank sensor could cause that, or am I barking up entirely the wrong tree?!

Hi. shear keys dont fall out in my experience...and crank position sensors do not normally cause no compression...Get another garage!...all that smart arsed stuff aside i"m sorry for your troubles man..The old guard here can help you if you give us facts..chin up old boy!...oh i sound so horrible and unsympathetic..it could not be further than the truth!..hj.

He doesn't think shear key has fallen out, more likely lived up to its name and sheared. I suggested crank sensor but he is same opinion as you, not likely to cause lack of compression. Thanks for reply.

I"m not in the doghouse am i?

They are. All Tors have B200F engines and all B200 engines have a raised crown piston that will contact the valve heads

It only takes half an hour to take the crank pully off and check the crank gear. It is the second check after checking the cam belt marks. Why mess about checking the valves are moving when it shows nothing, they would only stick if they were damaged way worse than any head I have seen on a redblock. Yes taking the oil filler cap off to confirm the cam is turning it worthwhile but only takes seconds.


Not the same kind of timing. No compression is cam to crank timing. Ignition timing is distributor but that gives poor running or no start but you will have compression

Your car is a 1992 Torslanda, which means it should have a set of round toothed pulleys and a matching round toothed belt.

This a replacement bottom cambelt pulley for your engine, you can see the little raised nub on it that locates the outer pulley (which has the belts for the water pump and the alternator on it, but critically the timing marks for setting up the cambelt on it) as well as the nub on the inside of the pulley, which locates the crankshaft pulley in the correct position on the crankshaft.

https://www.classicvolvoparts.co.uk/...BELT+271747%2E

The mechanic may have called it a woodruff key, which it sort of is, but a woodruff key is usually a separate piece that slots into position- the Volvo design has the two locating nubs cast as part of the pulley.

The weakness of the design is that those nubs are not particularly strong, and if the pulley is put into position and just held with a hand whilst the pulley bolt is done up with an impact wrench (rather than using the volvo tool to hold the pulley stationary in the right place and then do up the pulley bolt) the nubs can get sheared off- the result of which is the crankshaft pulley can twist around, moving the crank into the wrong place relative to the camshaft and the intermediate shaft.

Given that you just had some work done on the cylinderhead, which would have meant that pulley was removed, my guess is the above is what occurred- the pulley was held in position and an impact wrench used to do up the bolt, shearing the nub off the inside. The tightness of the bolt held everything in position for a while, but after a little while the pulley slipped round (and it doesn’t need to move very far) and now the engine won’t run.

As said above though, this shouldn’t lead to no compression at all, just compression at the wrong time- did the garage do a compression test with a gauge, or did they spin the engine over on the starter and just listen to it?

If: the cambelt is turning the camshaft, the plugs are sparking, there is fuel getting to the cylinders - then perhaps the above is true and the cambelt pulley needs to be checked and maybe replaced. But look for the obvious first, it might just be the fuel pump replay or the ignition amplifier. Back to my question above- how did the garage check for no compression?

Cheers

Not at all! You've been very helpful, I've learnt a lot.

Thank you for that comprehensive reply.

I spoke earlier to John, the mechanic and it's definitely the key which has sheared. I notice that the link you included is for 1993 onwards, my car is 1992 so I wonder if they changed the design for later models, John said it's definitely a separate key, not actually part of the pulley. I don't know if he did a full compression test but the way the engine spins on the starter I think it would be surprising if there's any compression. He also thinks it unlikely that there's been any consequent damage, which is something of a relief!

As the head was fully reconditioned I wonder if new valve springs could have been the cause of the key shearing; after more than 240,000 miles maybe the old metal was unable to cope.

It's slightly ironic as the engine, despite its high mileage was running like a dream, more power, better fuel consumption and very low emissions.

I hope it will all be seen to this week, I've been using the garage car, a little Micra, quite a lot, and it's a bit of a shock to the system after the Volvo!

No problem, happy to help.

Volvo changed the design of the pulleys and cambelt from a square tooth design to a round tooth design for the later cars - the round tooth cambelts have a longer service interval and are quieter in use. Obviously enough they are not interchangeable- the set of three pulleys (crank, camshaft and intermediate shaft) and the cambelt need to be either one or the other.

Your car should have a set of round tooth pulleys and belt, as they were used from around 1991/1992 onwards, but it’s easy to check- I’ve attached photos of what the two types look like - the shape of the teeth is noticeably different when viewed side to side.

Brookhouse have both types of crank pulleys in stock.

Cheers

Did you get this fixed?

Cheers

I've been meaning to write a follow-up, thanks for the prompt!

The replaced pin (key or whatever it's called) was loose so some remedial work needed to fix that. It turned out that there were some damaged valve stems so the head went back to the engineer who promised to replace at minimal cost. Car eventually back on the road after nearly five weeks, the delay caused mainly by the garage being very busy. I had a loan car for most of the time but it was a great relief to hear the distant hum of the Volvo engine again and it's running beautifully so I hope no more serious problems to come.

It turned out that the battery had come to the end of its life, so yet another expense! It was still under guarantee by a couple of months so hoping to recoup some of the cost - it had been bought and fitted in January 2021 by a relative so not sure what sort of response I'll get from the supplier.

Thanks to everyone who went to the trouble of replying to my original post.

Glad it's fixed and back on the road. :thumbs_up: