General: 850: Another "my 850 wont start properly since 2006" question

[John Brennand]

I have asked this same question on January 2nd 2007 but have still have not solved the problem!

My missus has an M-reg 2.0 850 20V which has had the following problem on and off since buying it in summer 2006 - occurring at infrequent and random times since then. When you try and start it (from cold) the engine turns over powerfully but it just wont catch. There are 2 solutions - walk away and have a cup of tea - come back an hour later and all is well - it will start and run normally and sweetly - for weeks. Or, do the long start process of continuing to try and start the engine with the accelerator depressed for about 2 minutes - when it will eventually catch - this is nerve jangling as the battery drain must be high ! At no time does the car ever cut out or die thereafter - all is just hunky dory once it's up and running.

Now, previous wisdom suggested it could be related to the "immobiliser" and possibly the antenna and I must admit I have not checked that yet - and hence this question. I wasn't convinced then that the car actually has an immobiliser fitted, although it has central locking - the car came (2nd hand dealer) with two non-fob keys - but that may be just because the dealer didn't have the originals and just supplied the cheap alternatives. There is a little light on the dash - which has flashed red once in the last 4 years ! Jod T5 gave info on how to check for the "Volvoguard" relay unit but I couldn't get the lower panel off below the steering column to take a look and check - and then the problem disappeared so I left it alone.

So now it's back I would like to nail it for good. Do these symptoms sound like an immobiliser issue to you guys. If it has one, then if I remove the ignition cowl I should see a ring antenna right ? Wisdom says replace it or take it off clean connectors and refit. I will try the latter - are there any removal/refit instructions posted anywhere or is all self-evident?

But here is the real question I have - if fitted, can I just remove the antenna and dispense with it ? Or will the car simply not start/run properly if removed/disconnected ? Should I try the same with the Volvoguard relay unit (if fitted)? We have never used remote locking and don't care if it is there or not.

Is there another way to simply disarm this system - fuse/relay etc, that I can try, to see if this rectifies the random starting problem?

Any other likely causes of this that are not immobiliser related ? Remember, it is a starting only issue - once running it is as sweet as a nut and starts and runs normally thereafter for weeks or often months.

Thanks again for any suggestions. John

[RollingThunder]

Hi John,

I think you have the same problem that made me sell my 850 2.0 20v...

The root cause is that the tappets get gummed up and so stick in the cylinderhead, leaving one or more valves partially open. Obviously this gives no compression in the affected cylinder/s and so no startup. The key identifier here is that the engine turns over much faster than normal when the tappet has stuck - due to the lack of compression resistance.

This happens infrequently, and once running the car will be fine, however if you fluff an engine start - ie release the ignition key when the engine has only just caught and then let it stall, then its likely that it'll be a pain to start due to the above issue. Similarly if you start the car from cold only run it for a few seconds, then switch it off, it'll most likely be troublesome. I had to do this to move my car away from the garage door so that I could get at my motorcycle - and with a sloping drive, pushing it away wasn't an option).

You can try using a good engine flush and oil change every month for a few months to try and remove the worst of the gum, or else pull the head off and do the job properly - remove and clean the tappets or even replace them outright as they are difficult to clean thoroughly.

I chose the engine flush method but in the end sold the car as it would fail at the most inopportune moments.

BTW Its a known problem particularly affecting the 2.0 20v (but isn't unheard of in 2.5 20v either) and Volvo issued a bulletin about it - I'll see if I can dig it up. I think it was in VADIS.

Sorry bud.

[s.hammond]

i second that mine's the same, but only if i start her up then switch off straight away which i now avoid! if i have to do this i let her run for a few seconds more and seems to avoid the starting issue. all i do when it does happen i just floor the throttle while starting whether that's right or wrong it works for me!

I've given mine 3 oil changes last year as mine hadn't been serviced for four years and seems to have reduced it quite abit.

best of luck, and don't rush and sell your 2.0 20v i love mine!

[RollingThunder]

Originally Posted by s.hammond

...best of luck, and don't rush and sell your 2.0 20v i love mine!

I run an 850R now

[John Brennand]

Originally Posted by RollingThunder

Hi John,

You can try using a good engine flush and oil change every month for a few months to try and remove the worst of the gum, or else pull the head off and do the job properly - remove and clean the tappets or even replace them outright as they are difficult to clean thoroughly.
.

Thanks guys. What procedure do you recommend for flushing the engine ? Put in a "thin" oil, rev the engine for 1/2hr and drain -perhaps ? What specification of Mobil1 oil would you recommend to leave in - or is there only one 1 ?

Re the tappets - is replacing them a big job? - I have never done it but am fairly useful with a socket set and a Haynes? Or, how long would it take a competent mechanic at a "good" local non-Volvo garage to complete - which is what I use - so I can gauge the ££. It has to go in there for MOT next month.

Thanks again. John