Valve seat recession - questions

[pistrix]

Hi Everyone,

I apologize but I just have to ask for an opinion again:

I have a 95 850 2.5 20V and I've decided to install Prins LPG system. The car has 270,000 kilometers and I plan to have it for at least 100,000 km more. Is it worth spending 300€ for the Valvecare system? The installer strongly recommends it but when I asked him if it is really necessary, he wasn't very convincing. His only argument was that it is better to have it, just in case...

Thank you.

[volvobaggen]

From what I understand after reading a lot on this topic, this is a "true" volvo engine with hardened valve seats that runs fine without any valvecare/flashlube.

[capt jack]

Well my 1997 V70 2.5 10v has 263,000 miles, which is 423,000 km. It has been running on LPG since 53,000 miles, which is 85,000 km, so that is 338,000 km running on gas.

It has no valve lube system, and I guess that if one had been needed I'd have found out by now!

Cheers

Jack

[classicswede]

and at 300 euros you are getting ripped off. Should only be around 50-100 max for a non turbo engine.

[pistrix]

Thank you guys for your answers. I appreciate your help.

300€ because it is supposedly an advanced system with a high pressure pump (I don't know the details)... I don't care anymore.

fyi: http://www.prinsautogas.com/en/produ...valvecare.html

[pistrix]

Hi guys,

as of last week, I drive on LPG (Prins without valve lube system). photo

At first, the engine ran quite rough on idle and the transition from the idle was also very jerky, especially when the engine was cold. However, thanks to this forum, I was prepared to take action: I installed fresh NGK BKR6ES sparks (will try Denso next time as suggested by capt jack on this forum), changed the ignition cables (previous were from 1995 and with a couple of cracks on suppressor connectors), I thoroughly cleaned the distributor cap and rotor (It is quite worn with a tiny crack on the rotor so I will install a new one today), I cleaned the idle air control valve, the throttle body and the flame trap tube (there was no flame trap). I've also visually checked the MAF sensor and it looked intact.

Now the engine runs almost perfectly on LPG and I almost can't tell the difference when driving on LPG or petrol. Although the transition from the idle improved significantly and is now better than it was on petrol before the conversion, the idle is still a little rough when the engine is warm and very rough during the first few minutes when the engine is cool. On petrol, the idle is also not as perfect as I suppose it should be (the RPM needle occasionally jumps down and up for about the width of the gauge needle) and it seems that LPG simply amplifies the issue, especially when the engine is cool.

Do you have any idea what else I should check/do/fix? As I said, I will change the distributor cap and rotor today but I have a feeling this is not the reason.

Cheers,
Jan

[classicswede]

Sounds like you have covered most of the possibles already.

The new cap and rotor may well make a differnce.

I would also run some injector cleaner through the petrol system.

After that and you are happy with how it runs on petrol go back to the installer and ask him to check the mapping.

[capt jack]

One more thing to try - have a look at the idle air control valve, give it a good clean and make sure that it works OK.

If it's sticking that will certainly mess up the idle.

Cheers

Jack

[volvobaggen]

About spark plugs, I previously had Denso K20PR-U(came with the car when I purchased it 2 years ago), and changed to NGK BKR6ES because it was on the classicswede recommandation list.

Im probably just fooling myself, but I have a feeling the engine ran slightly better with the denso´s.

[volvobaggen]

Capt Jack, what spark plug gap did you use with your B5252S engine?

I didnt bother controlling the spark plug gap on the NGK´s, and thinking back, they might have been a little on the wide side from the box. Maybe it can explain why my engine is a bit jerky under load on low rpm.