volvo 4.3gl exaust riser valve problem

[schnorrd]

2000 volvo 4.3 GL motor. there is a valve on the side of the exaust riser, with a hose connecting it to carb. This valve is suppose to only be one way allowing air into riser to dissipate moisture at low rpms. One went bad and was blowing exaust into carb. replaced it and new one went bad after using for an hour.
Does anyone have any ideas what could cause this valve to go bad?
Motor runs great with new valve in, no overheating, good oil pressure,risers and manifolds replaced about a year ago.
Thanks Doug

 

[JustJason]

Re: volvo 4.3gl exaust riser valve problem

what "valve" are you talking about? are you just talking about the crankcase vent off of the valve cover? Take a picture!!

 

[schnorrd]

Re: volvo 4.3gl exaust riser valve problem

Thanks for reply, but no I am not talking about the pcv valve on crankcase.
On this particular year Volvo 2000 4.3 Gl there is a valve on side of the exaust riser near the top of it, that then has a hose attatched to it which leads to the air breather just like a pcv valve normally does.
I had never heard of this before and never paid attention to it until it went bad. Once it goes bad the exaust pours out of it melts the rubber hose and fills the engine compartment with exaust. The part is only about $40 and there is one on both risers. I replaced it and engine ran great for about an hour until new valve went bad again. I can plug it with a rag and engine will run as if nothing is wrong, So I am trying to see if anyone has ever heard of this before I go to expense of tearing down risers and manifolds on a wild goose chase as to what would cause this normally one way valve to become two way.

 

[bjcsc]

Re: volvo 4.3gl exaust riser valve problem

Where are you? Is this some kind of California EGR system? I would buy a brass pipe plug for the riser and be done with it. I've never heard of such a system...

 

[newport dave]

Re: volvo 4.3gl exaust riser valve problem

Don will probably know for sure, but I believe they put those on at the same time they removed the exhaust shutters, to prevent vacuum from forming in the exhaust (or something along those lines).

 

[dasnively]

Re: volvo 4.3gl exaust riser valve problem

Schnorrd,
Don't worry, you don't have a "one off" engine. I also have a 2000 4.3GL and it has the valves. I only realized what they were when I pulled one off to get the valve cover off and then started it without it installed. I would have to think you got a bad one if it burned up that fast. How hot do your risers get while the engine is running? I can put my hand on mine while it is running. You have good water flow to the manifold risers?

 

[schnorrd]

Re: volvo 4.3gl exaust riser valve problem

I did not put my hand on the riser but I did take a reading with an infared thermometer and both risers were approximately 170 to 175 degrees. The one with the bad valve actually cooler than the other one. however the valve itself when I reached down and pulled the melting hose off blistered my skin. I have actually had someone else suggest plugging the hole and doing away with the valve, but I am afraid that what ever is causing the problem may do more damage to something else. Plus I would love to know what the actual purpose of this valve is and does it maybe extend the life of the risers by allowing the water to drain out when engine turned off. Any more suggestions out there?
Doug

 

[newport dave]

Re: volvo 4.3gl exaust riser valve problem

175 is too hot for an exhaust elbow, you should be down around 100 or so (idling with no load). That may be why the valve is failing. I would check your seawater pump, sounds like it's not doing it's job.

 

[Don S]

Re: volvo 4.3gl exaust riser valve problem

The risers should never get that hot! Was that while running under full load? or just on muffs in your driveway. Big difference.

 

[schnorrd]

Re: volvo 4.3gl exaust riser valve problem

That was immediatelly after running at full throttle with 7 people aboard for about 20 minutes. The temperature on gauge on dash also read about 170 to 175. Does this make a difference or do you still think its the raw water pump.
Recirculating pump was replaced with the risers about a year ago as well. All parts were genuine Volvo parts not after market.
Thanks Doug

 

[Don S]

Re: volvo 4.3gl exaust riser valve problem

The impellers should be replaced every other year. How old is your's?

 

[schnorrd]

Re: volvo 4.3gl exaust riser valve problem

mine is probably at least two years old, which brings me to next question.
My mechanic says that the original style raw water pump on my 2000 4.3GL had lots of problems and recommends replacing the entire pump not just the impellar with an upgraded model at the cost of about $350 just for pump. Seems like alot to me for a tiny raw water pump, what say everyone else.
Thanks Doug

 

[Don S]

Re: volvo 4.3gl exaust riser valve problem

Seems like alot to me for a tiny raw water pump

Well, they aren't priced by size. If it's bad, replace it, if not don't. I can't hold it, inspect it and look it over or see how your engine was acting. So really can't say for sure if the pump needs replaced or not.
But there was no service bulletins that ever said anything about any 2000 pumps not working.

 

[schnorrd]

Re: volvo 4.3gl exaust riser valve problem

I appreciate the input. Mechanic is coming today. The engine was and is not overheating but I guess its possible that there is enough flow to keep engine cool but not enough for risers? we will pull it apart today and I will let you know.
Thanks Doug

 

[DjArgyleFan]

Re: volvo 4.3gl exaust riser valve problem

How did you sort yours in the end? I also have an issue with those valves & can't seem to find out which way they blow or what there purpose is. Did you ever find out?
Martin.

 

[Don S]

Re: volvo 4.3gl exaust riser valve problem

You need to start a new thread with your question, the original poster here never came back after his last post. Besides, it's from 2008.