Timing belt snapped - what are my chances?

Post by **crimsone** » 02 Dec 2005 07:35 pm

I drive a Volvo 340GL 1.7 (B172 engine), and the recovery man that brought me home just now has told me that the reason my car suddenly stopped was because my timing belt has broken. I know some volvos have a "non-interferance" timing design, but I don't know if my engine is one of them - does anybody know?

He also told me that if it's a non-interferance timing design, then I should have no problems and it should just be a case of fitting a new belt, but if it doesn't have clearance between the valves and pistons, then there is a small chance that it will turn out ok, but don't hold out to much hope as the top end is probably destroyed.

Can anybody tell me just what my chances are with this car?

Post by **pettaw** » 02 Dec 2005 07:43 pm

Low I would say. The Renault unit in this car is an interference design. I would buy a new cambelt and fit it and try the car, if it runs then great. If not then prepare yourself for a whole lot of work. most probably a complete stripdown. If you can't do it yourself, its not economical to pay someone else to do it and I would scrap the car and buy another one.

This is a tough lesson to learn for everyone on here. Change your cambelts at or before the correct intervals, because one 20 quid belt snapping means potentially 1000 quids worth of engine damage.

Post by **volvorsport** » 02 Dec 2005 08:54 pm

a couple of valves , a timing belt and a headset wont be that expensive , you could just fit another head ?

its the labour cost , and about 8 hrs would see it done , if the head has to come off

Post by **crimsone** » 02 Dec 2005 10:12 pm

Well, it's been a pretty solid car in fairness to it, but given that I only bought it for £200 (a pretty good price

) I think the only thing worth trying on it would be a new head from a scrapyard to be honest, which would be a very hit & miss affair really.

With that said, if I did attempt to repair this car, what would be the chances of damage to the pistons themselves as a result of striking the valves?

Post by **redline** » 02 Dec 2005 10:24 pm

its impossible to say without removing the head , the cheapest option is to try a new belt first ( you have nothing to lose )
IIRC on the old ford pinto engines you were screwed if your belt snapped on a 1600 ohc but ok if it happened on the 2.0 because there was more clearance between the valves and piston crowns

Post by **sven360** » 06 Dec 2005 12:46 am

redline wrote:its impossible to say without removing the head , the cheapest option is to try a new belt first ( you have nothing to lose )
IIRC on the old ford pinto engines you were screwed if your belt snapped on a 1600 ohc but ok if it happened on the 2.0 because there was more clearance between the valves and piston crowns

Not strictly so, I think it may be the other way round-I snapped belt on 1600 cammy cortina but new belt fixed it- well lucky

roll the dice and see if your lucky it should be less than 20 quid and a bit of time-best of luck

Post by **shimon340** » 06 Dec 2005 01:19 am

hi there,

if the pistons hit the valves then you will probably have a few bent valves. The 1.7 engines have pistons with bowls in them - instead of a flat top they are concave - so hopefully the damage wont be too severe. Removing the head is just like having to change the head gasket. The valves for these engines are about £5 each and there are only 8 and I doubt all of them will be damaged.

You'll need new bolts for the head as I think the 1.7 uses stretch bolts ie bolt that can only be used once, to bolt head to the engine block. The volvo redblock engines ( from the bigger volvos and the 360 ) use reuseable bolts- far more sensible!!

you'll also need a head gasket if you are taking the head off and also new gaskets for the inlet and exhaust manifold...

if you can do the work yourself, then the car can be put back on the road. Alternatives are instead, finding a new engine from a scrapped 340 or buy a cheap 340 from ebay and swap the engines. I wouldnt think damage to the head would be teminal except for a few valves.......

Post by **shimon340** » 06 Dec 2005 01:23 am

check this out in the "offers" section

Post subject: b172 - b18 cylinder head

Website · Post by **antiekeradio** » 06 Dec 2005 05:07 pm

1.7 is almost guaranteed to have at least a number of valves _bent_ if the belt snaps;

perhaps these images will clarify:
(yes this was my own car at the time...)

you can see the pistons get a good knaw as well.

In this case the belt roller blocked. the belt did not snap but loose more than half of its teeth. result is about the same, I would guess...

my solution:
(expense: not.. only had to help stripping the donor car)

ran beautifully again with this engine.

Post by **RandomHero** » 06 Dec 2005 06:18 pm

Ouch, did that happen to your car? Never knew that before..

Website · Post by **antiekeradio** » 06 Dec 2005 09:04 pm

yep.. suddenly a metallic noise on the highway (ball cage of the bearing getting caught between the balls and outer ring)

it happened so fast I even had no time to left to press the clutch..

then the noise suddenly stopped and the car felt like I was braking lightly.
rolled out; depressed clutch, engine noise came to a halt reeeeaally slowly (like some tired old vacuum cleaner when you switch it off)

tried to start it again but the starter revved it to 400 rpm, effortless. nothing else happened. my conclusion; 'whoops.. no school today'

Post by **huskyracer** » 08 Dec 2005 08:38 pm

Have to agree, they usualy make a mess when the belt lets go, but it is always worth trying one first, but be very carefull when you put it back together, the locking pin that fits in the crank will also go into the ballance holes in the crank webs, so it looks like you have timed it up right but the crank is in totaly the wrong place, if you try to start it like this, if you didnt have bent valves, you will now! before starting it up, turn it over with a spanner on the crank (at least two complete turns) to make sure nothing touches. From memory, the hole in the crank is at tdc, so you can check its in the right place by CAREFULLY putting a thin screwdriver down no 1 plug hole and gently rotating the crank untill the screwdriver is at the highest point, then the timing pin should slide in with minimal movement of the crank.

Post by **Wiktor** » 08 Dec 2005 10:57 pm

I'm really sorry...

Website · Post by **antiekeradio** » 08 Dec 2005 11:37 pm

oh and BTW (wonder why nobody made any remarks about it)

the second picture (of the pistons) clearly shows that the right hand side one (nr 1 from flywheel) is seriously burned and pitted.

wonder if this would have caused trouble later on, in this case it didn't have any time to do so.

The cause for this pitting was false air coming past the manifold gasket. the manifold nuts are of a very flimsy construction, and a few of them were missing/very loose.
It also caused the car to idle on 3 cilinders, all the time.

apparently, the air leak caused cilinder 1 to run lean all the time... with result all this pitting etc. The cilinder head was even worse.
(pics available on request)

Greetings Wouter

Post by **shimon340** » 09 Dec 2005 02:08 am

hi wouter!

yeah, I'd be very interested to see some more pics of your engine. Im just starting to learn about the 1.7

Ive got a 1.7 but I think the head gasket has gone. When I got the car it had no antifreeze in so I draining the cooling system and topped it up with 50:50 anitfreeze ( there was still some water in the engine so I wanted to ensure the antifreeze would be strong enough ). After running the car a while there was black sludge in the water which I suspect is oil or maybe the result of someone putting a radiator sealant called "Bars leak" into the coolant at some point - before I got the car the previous owner also replaced the radiator.

When I start the engine now - the car is in storage - I get mayonaise on the oil filler cap. Before I start the head gasket repair I'd like to know for sure that it has failed.... you get mayonaise from short journeys or sometimes when a car is just warming up. The black gunk in the oil is a suspicious thing though.

the engine has done 41,000 miles. I was told by a volvo mechanic that when the 1.7s were new there were a lot of cases in the first few years with new engines getting a slimey black substance in the water. This was caused by a fault with renaults manufacter where they werent washing the sand from the blocks sufficiently well- this fine sand was then forming a sludge in the engines. He said seeing that this engine has only done 42,000 it maybe the end of the is sludge problem. i was told to drain the coolant and simply flush the water system until no more black sludge came out. Also, this black sludge floated on the water... so it seems to be oil....

I've heard the "burnt valve" or "burnt piston" thing with 1.7 engines before.... so the fault is a air leak past the inlet manifold... I'll check mine... if I do the head gasket I'll have to change this gasket anyway....

If a valve or piston is burnt is it irreparable? ie do you have to change the valve or piston? what problems does it cause if you still use it? could the soot be removed by cleaning?

look forward to seeing more pics of the engine.

did you fit a new head from another engine in the end?

i've heard that with these aluminium headed engines like the 1.7, a lack of antifreeze causes the aluminium to corrode which leads to head gasket failure. As my car had no antifreeze in it when I got it, I suspect this is why the head gasket has gone

Are the heads aluminium? are they alloy? if I needed to repair it what metal should be used? is it necessary to skim the head before replacing it on the engine?

thanks!!

Shimon