Is the Rover V8 an interference engine?

Magicdrshoon · Post by **Magicdrshoon** » Mon Jul 06, 2015 2:00 pm

Hi all.

Is the Rover V8 3.5lt an interference engine? i.e. If the timing is completely wrong, will the pistons hit the valves?

I've been trying to find this out for a little while (without actually taking mine apart!), and all the posts I've read where someone else has asked the same question, the responses discus other possible causes of the symptoms suspected to be due to pistons hitting valves, without actually answering the question! I saw the post recently about the bent pushrod on a 5lt V8 from a TVR. That's a different engine isn't it?

I have a 109 Landy with an engine out of an SD1, and a while ago I adjusted the timing on it and got it running better than it ever had.

A week later I tried to start it (just to keep things moving), and it didn't want to know. After flattening the battery, I hooked up some jump leads and eventually got it to start, although it didn't actually respond to the throttle, and slowly reduced in revs until it cut out (over the period of around 10 seconds).

After that it didn't fire at all.

I gave it to a local Landy-friendly garage who said that after a couple of hours of tinkering, they got it started but it didn't sound at all right, with metallic rattles and knocking.

He said that the bill could go into four figures, stripping down the engine and diagnosing what the fault was, and suggested that I take it home, remove the timing cover and start there.

I did that (not the simple 1 hour job I expected! Took me all day!) and found that the timing chain was so stretched that it sometimes jumped a tooth, and sometimes wedged itself.

I'm wondering now if I get a new chain and fit it, after setting it all up, is there a good chance that it'll be fine, or is their likely damage to the valves?

When I turn the engine over by hand, it doesn't get stuck anywhere, but I do hear the hissing of air escaping on compression stroke...

Or shall I just bite the bullet hand have it out and rebuild it??

Thanks in advance!

harvey · Post by **harvey** » Mon Jul 06, 2015 2:21 pm

Magicdrshoon wrote: Is the Rover V8 3.5lt an interference engine? i.e. If the timing is completely wrong, will the pistons hit the valves?

Yes. Last one I did that had a timing chain jump teeth, after I fitted a new chain and gears a compression check revealed zero compression on 5 out of 8 cylinders because of bent valves.

Magicdrshoon · Post by **Magicdrshoon** » Mon Jul 06, 2015 2:45 pm

harvey wrote:
Magicdrshoon wrote: Is the Rover V8 3.5lt an interference engine? i.e. If the timing is completely wrong, will the pistons hit the valves?
Yes. Last one I did that had a timing chain jump teeth, after I fitted a new chain and gears a compression check revealed zero compression on 5 out of 8 cylinders because of bent valves.

Bugger.

Spongo · Post by **Spongo** » Mon Jul 06, 2015 3:43 pm

If the timing chain is that bad chances are the rest of the engine is really tired as well so it would make sense to rebuild it or at least do some more investigation.

Where are you as there may be some members on here that are local and can help

DaveEFI · Post by **DaveEFI** » Mon Jul 06, 2015 3:59 pm

I'd first fit a new chain (and cogs if needed). Since you've already got to it.
Then see if it now runs ok. Check the ignition timing is correct afterwards, as if it has been set with a worn chain it will also be wrong.

These engines can still run pretty well even when well worn.

You've got nothing to loose.

Magicdrshoon · Post by **Magicdrshoon** » Mon Jul 06, 2015 4:49 pm

I'm in Beds, near Leighton Buzzard.

I need to have a think on what to do next.

I get very little time to tinker at the moment. So I could use a day (maybe more with the speed I work at!) to put it back together and set up, to see if it still works, with a relatively high risk of it still not working.

I could pull the engine out and rebuild it, but then the rest of the Landy could do with a restoration so if I do that I may as well get on with doing the rest of it.

I could buy another V8 and swap it out.

Or find a diesel engine (which would have to outperform this SD1 engine by a significant amount) and put that in. Practically diesels are great for 4x4s, but they don't sound half as good!

Thanks for your help!

ChrisJC · Post by **ChrisJC** » Mon Jul 06, 2015 5:13 pm

Are you sure the standard 3.5 is an interference engine? I didn't think it was, not that I've ever tried it.

Chris.

kiwicar · Post by **kiwicar** » Mon Jul 06, 2015 5:22 pm

Hi
Personally I would look on ebay for a low mileage second hand 3.9 replacement, make sure you hear/see it running before you buy it but there are a couple on for about £650 and I think this will be the cheapest/quickest option. Replacing timing gear on an old worn out 3.5 just seems a way of throwing away money. If you suspect the chain has jumped then I will bet several valves will have hit the pistons, it will be take you as long to investigate it as change the engine. TBH looking at new factory replacement engine prices pretty rules out that option http://www.ebay.co.uk/itm/Rover-v8-3-5- ... 3aac2d54d1 and time will rule out a rebuild so the only way forward is a second hand unit.
best regards
Mike

kiwicar · Post by **kiwicar** » Mon Jul 06, 2015 5:30 pm

Hi
From memory small valve P6 based low compression engines with low lift cams like the stage 1 V8, 101FC and MGBV8 were clearance engines provided the lifters did not pump up with over revving, which they generally didn't if they cam had jumped a tooth or two. However pretty everything else was an interference engine as the valves opened over the raised part of the piston at the edge and there was enough lift in the cam without the lifters pumping up.
best regards
Mike

DaveEFI · Post by **DaveEFI** » Mon Jul 06, 2015 6:00 pm

Must admit the thinking if the engine was so worn as to jump a tooth, wouldn't the cam be worn too - so nothing like as much valve lift?

kiwicar · Post by **kiwicar** » Mon Jul 06, 2015 6:43 pm

Hi Dave
I think you need to consider a new career in sales!

best regards
Mike

paul c · Post by **paul c** » Tue Jul 07, 2015 6:35 am

I replaced my old 3.5 with a 96 3.9 but fitted carbs back on it, definitely a big improvement on the 3.5

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Is the Rover V8 an interference engine?

Is the Rover V8 an interference engine?

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Re: Is the Rover V8 an interference engine?