Cam belt timing marks

[bob12]

Originally Posted by Laird Scooby

A few poor unfortunates who've had a B200F bend valves on them!

We can all bend a valve but how did they do that? Where is something authoritative to say that a B200F is an interference engine. Bob

[mocambique-amazone]

Hy Bob
https://www.volvoforums.org.uk/showthread.php?t=302747

B200F are hard to find in Germany. Only if imported from Italy.
I did have 2 at minimum with bent valve, thought the shaved head as a reason. Now I did learn something. They are interference engines
B200FT I don't know. One is in my workshop. I will have a closer look.
Stay free from corona, Kay

[griston64]

Originally Posted by Laird Scooby

Minimal rotary tension on the camshaft that could cause it to jump as the tensioner is released Mark. Brown trouser moment when that happens!

Many moons ago while changing the belt on my Rover, one of the valves in the rear bank was open just enough to cause it to shut on spring pressure from the valve springs, turning the cam backwards slightly and causing a trouser-filling metallic clang.

I got the job finished and started it with a little trepidation but i got away without any problems.

The other reason is that if something does go wrong for whatever reason, doing at @ TDC #1, you know where the various engine parts should be so won't have a problem starting from scratch.

I know what you are saying Dave but that therefore makes the handy method ( that Volvo themselves put in place ) to re tension pointless ?

[Laird Scooby]

Originally Posted by bob12

We can all bend a valve but how did they do that? Where is something authoritative to say that a B200F is an interference engine. Bob

That i can't answer Bob as i don't know all the facts, however there have been a couple of reports on here of people with B200Fs and all 8 valves bent!

How it was managed, whether the head had previously been skimmed to within a nicron of its life or what i don't know. HOwever, one person reported they'd never had the head skimmed although they had the head gasket done during the life of the car. Read into that what you will.

I've seen a head (not Volvo) where the owner was driving at 150mph ish and burned a hole in the piston, said lump of molten alloy somehow jumped onto the crown, bending at least one valve but also causing the timing belt to jump and the other 15 valves to become bent. It also suffered HGF, from what we could deduce the lean mixture (old, clogged injectors and a bit too much boost) caused the overheat and HGF and then the resultant melted piston etc.

Because it was the turbo version (and the pistons were shorter above the gudgeon pin than the n/asp version) it was listed as a non-interference engine. The n/asp was listed as interference though.

My theory is that wear in the gudgeon pins, big ends and a heavy previous skim (obvious when we measured the depth of the head) removed the safety cushion that would otherwise have been there.

Perhaps something similar (but maybe not so drastic) has happened with these B200Fs the reports are about. Purely conjecture butthat's all we have sadly.

[mocambique-amazone]

Originally Posted by griston64

What difference would that make ? You are only adjusting the tensioner. The cam cover is also in the way when you do this through the hole where the bung goes

On some position of the camshaft the tension is on the wrong side of the belt. The springs of the valves are more strong than the tensioner. Result will be a sloppy timing belt.
You want to do something right and the result is worse than doing nothing.

[Laird Scooby]

Originally Posted by griston64

I know what you are saying Dave but that therefore makes the handy method ( that Volvo themselves put in place ) to re tension pointless ?

True but maybe Volvo are thinking of all possible scenarios?

It could also be the natural point of least tension on the timing belt because most other valves are closed, i haven't looked into it.

Volvo do say to do it at #1 TDC and i know on my Rover, once the tension has been set at TDC, turn it twice then turn it past TDC to a blue groove on the crank pulley (line it up with the pointer on the timing cover) which is about 18 deg ATDC and then reset the tension, turn it twice more and check/set the tension again so presumably a similar idea.

Sometimes the reasons aren't obvious but failure to observe the procedure results in serious pain in the wallet area. On things like that, unless i know the reasons why and can take them into account, it's a case of follow the procedure, no matter how daft, pointless or futile it may seem.

[Laird Scooby]

Originally Posted by mocambique-amazone

On some position of the camshaft the tension is on the wrong side of the belt. The springs of the valves are more strong than the tensioner. Result will be a sloppy timing belt.
You want to do something right and the result is worse than doing nothing.

Pretty much what i guessed at then Kay?

[bob12]

It is my personal view that B200F's in their original state were not interference engines, but subsequent head skimming etc is the cause of any problems. Somewhere I had a very detailed list of all Volvo engines of this era and past interference and not. I know for a fact it wasn't there or any other data sheets as I was particularly interested in the B200F. Unfortunately, it all went the way of most things I didn't back up when my previous computer imploded. Bob

[Laird Scooby]

Originally Posted by bob12

Unfortunately, it all went the way of most things I didn't back up when my previous computer imploded. Bob

Feel your pain on the computer problem thing Bob. A few weeks ago, the monitor on my main PC (Samsung 22" widescreen) went belly-up so as a temporary measure i swapped it with my other PC (still running XP and has certain things on i can no longer get and/or use on Win10 or Linux which my main PC runs) that i use occasionally.

It came the time that i needed the other PC so i investigated the possibility of fixing the Samsung 22" and decided that for the cost, i could have a refurbished monitor delivered from ebay.
Ordered it yesterday, it arrived today, did the basic test and the monitor seemed ok so tried to turn the PC on - dead.

Trying the obvious first (the power lead) i put the lead from the monitor into the power socket on the back of the PC to be met by a flash and a bang from the PSU in thebottom of the PC case.

Sods Law or what!

I could send the (now spare!) refurbished monitor back and get a refund but it would cost half of the refund to send it back (if not more!) so i'll keep it as a spare just in case.

Meanwhile i'll explore the possibility of fitting the HDD from my old PC into my main one as an extra and bin the remains of one of Alan Sugars finest (the old PC is a Viglen) and/or find a secondhand PSU or something. If nowt else, i'll repurpose the case as something or other useful if possible. The main thing is the useful stuff on the HDD, maybe one of those external HDD adaptors/cases would be the answer..........

[bob12]

Originally Posted by mocambique-amazone

Hy Bob
https://www.volvoforums.org.uk/showthread.php?t=302747

B200F are hard to find in Germany. Only if imported from Italy.
I did have 2 at minimum with bent valve, thought the shaved head as a reason. Now I did learn something. They are interference engines
B200FT I don't know. One is in my workshop. I will have a closer look.
Stay free from corona, Kay

Thanks Kay. I have two B200F's (LH2.4) in 745's that came direct new to the UK from the factory in Belgium.

It was a common engine spec in 1990 in the UK for company car personal tax purposes.

One is roadworthy and the other a breaker. Fortunately, I have never had to take the heads off. Personally, considering what I have seen over the years I reckon any problem with crunchy valves is due to skimming or changing the original head spec in some way.

Bob