I found the following post on a Volvo UK site. Tried it and it has worked great so far. My 1993 850 would start then not start if driven a short distance and then would on occasion be hard to start then when it would start run very rough. At least I now think I know what the problem is. Hope this helps someone else.


Many of these cars suffer difficulties starting, especially when the engine is only run for a short time then switched off, and an attempt is then made to restart it. It is inadviseable to start any car with a catalytic converter in order to move it a short distance. The ECU's cold running sequence (which is designed to protect the catalytic converter from unburned petrol) cannot cope with this and having detected too much raw fuel in the xhaust, will shut the engine down.
Another cause, especially on the 850 models, is that the hydraulic tappets do not close properly when the engine is switched off. Oil gets behind them stopping them from closing fully. This means there is no or little compression in the cylinder when there is an attempt to start the engine again. One cure is to remove the plugs and squirt engine oil into each cylinder then replace the plugs and start the engine. The oil helps seal any gaps under the valves and give adequate compression in the cylinders.
Another cure is to use Mobil 1 engine oil all the time. This is thinner than other oils and will allow the tappets to close properly. If you change to Mobil 1 oil be sure to run the engine at 3,000rpm for about 20 minutes to ensure the oil gets into all the small channels in the engine.

 

Did you post this here but in another thread too ?? Seems it's the second time I've seen it and the first time I let it pass but the second .......

I've seen engine problems where so much fuel is dumped into the exhaust the cat is glowing red and most likely melted or close to it and the engine would have kept running right up to the point of the cat substrate melting and plugging the exhaust. Bad plugs, shorting wires or acrhing inside or outside of the cap can all be problems that pour raw fuel into the exhaust. I don't think the Volvo's downstream o2 sensor will tell the computer to shut down.

I work on cars at home and it's common to start and move a car 20 feet and shut it off and them have to move it again in a couple minutes as I don't have much room. Never had the type of problem your post refers to including at work where all mechanics start and shuffle cars around daily.

Why do you think Mobil 1 synthetic oil is any thinner than any other synthetic oil of the same weight, straight or multi ?? The whole reason there are different weights is they are designed different. A 10 W 30 conventional oil of any brand should be the same viscosity (thinness) as a synthetic blended oil of any manufacturer as a pure synthetic of any manufacturer including Mobil 1. They are all the same thinness or thickness if the weight(s) is the same.

The lifters in our engines adjust themselves by using oil pressure to "pump up" (get physically longer) and automatically adjust. When the engine is shut down the oil pressure drops and the oil drains to the pan and the lifters can't expand to hold the valves open. Unless Volvo is drastically different under that valve cover all hydraulic lifters work the same way. Lifters can stick and in that case a valve could possibly be held open but it would be one that stuck affecting one cylinder and it would still start it would just be unbalanced when running due to the dead cylinder.

If the valve is stuck open how is oil squirted into the cylinder supposed to "seal" the valve against the compression built when the piston comes up to TDC??

It takes 20 minutes at 3,000 RPM for the oil to reach all the "places". Every oil change I do I've never run an engine on high idle( higher than high idle actually), sitting still to circulate the oil before driving. Has anyone actually done this ?? I pour oil into the filter before I screw the new one on just to make sure I get pressure as soon as I can and I'd never think of running an engine at that high RPM for 20 minutes right after an oil change. I wouldn't run it at at that RPM for any reason for 20 minutes.

Now the reason I passed it over the first time is I was recently burnt telling someone all cars have a high and low side service port to the AC systems and up till this Volvo I've always had both ports to hook up my manifold gauges to. Cars, pickups and large trucks but NOT on a Volvo, low side only when I went to look.
Soooo, I may have missed something in my research on Volvo's and I'm going off what I know from everything else but if you're going to post something to try and be helpful you should at least understand what you're posting. I could be wrong but I don't find anything I agree with here.

 

Lots of stuff gets repeated on forums that is nothing more than old wives tales (apologies to any old wives in the audience). Part of the fun of hanging out here is getting the chance to debunk it..

Starting a car and not letting it get up to operating temperature is always bad in general. Especially in cold weather; if the "run" period is very short (less than a few minutes) the engine won't get out of its cold start cycle. The subsequent rough running is caused by the plugs being partially fouled. Also ignition systems on these cars aren't the strongest (hence the sensitivity to no bigger than 0.028" gap).

The rest that stuff is BS. We do appreciate you trying to help others barnlofter but it's best to vet the info before you pass it along...

 

My car does as described. The starter will not engage and crank the engine if car is moved a short distance and then shut down. One has to wait a while then it will crank. This explanation fits my cars condition. As far as the oil is concerned I found several post on other sites, mostly European describing the lifter problem as a very common condition of these cars. I believe when they refer to "thinner oil" what they really mean is oil viscosity. I noticed they spell tires, "tyres" and I did not feel the need to complain. The fact is the car will drop compression on all cylinders if allowed to sit in hot weather. Since using the synthetic oil I have not experienced this problem at all. I believe this is due to the lifters not sticking because of the synthetic oil. I am not a Volvo expert as some here, I have owned only three, but I have owned a shop 30 years and am always open and not closed minded from other mechanics no matter where they are from. I searched this forum and found no logical explanation for the way my 850 acted. I copied and pasted the post above directly from a UK Volvo site, their words not mine. If you had a better explanation post it and do not waste energy throwing rocks at me........

 

Wow dude; not throwing rocks or anything else; just expressing my opinion about what you posted. Most of which was anecdotal w/o logical explanations or facts to back them up. And I knew (took you at your word) that you copied it from another site; therefore my comments were directed toward the content; not you personally.

And please help me understand exactly what "the issue" is that you're talking about (from your last post):
I am assuming you're talking about two different issues, yes?

1. The starter doesn't work if there's too much raw fuel in the cat. I assume you're suggesting the ECM keeps track of how often the engine is started and shuts down the starter if attempted too soon after earlier run? Possible I suppose but never heard of anyone encountering that.
2. Too high viscosity engine oil causes loss of compression on static engine causing subsequent hard starting. Again, never heard of anyone encountering that.

So which problem are you having? You insist you've experienced problem #1, but haven't since you changed the oil that you were using, which is the supposed solution to problem #2? Certainly you're not proposing changing the oil viscosity was solution to problem #1 are you? If so would like to understand how that works...

Don't have to be a volvo expert for any of this; just need to understand how internal combustion engines (ICE) work in theory and practice. Sure, experience is always beneficial when trying to diagnose specific idiosyncrasies, but ICEs have been around for quite some time and they're pretty well understand...

 

The starter issue is still there. The change of oil did not effect it at all. If you start the engine then cut it off too soon the starter will not engage. The lights in the dash will light up but no power goes to the starter. I am careful not to turn the engine off too soon after starting. That is issue one.

Issue two is the complete loss of compression on all cylinders after the car sits overnight. Excessive cranking of the engine and the engine will gradually build compression and run. After the car is started the first time it will not give any trouble the rest of the day until it sits again overnight. I tried the Mobil 1 High Milage oil and it helped for a couple of days. This morning there was again the complete loss of compression on all cylinders. Damn!! It runs great with plenty of power once she does start. That is issue two.

I have read on many forums that both these issues are very common for the 93 through 97 850s.

barnlofter

 

Just read online that the injectors have been know to stick open in the 850s and wash the oil down from the cylinder walls causing a loss of compression. If so it seems odd to me that all injectors would "stick" open at the same time.

 

I have a similar problem and sure not related to oil. If I start the car to move from the garage and turn it off it may not start again perhaps until the next day. There is not even a click from the starter engagement almost like a security shut down. This is a 1995 T5R with about 80k miles. Was the ecu advanced enough in 95 to shut down due to converter not being hot enough? Once driven for awhile I do not seem to have the same problem. Overall the car runs good otherwise.