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Volvo 740

If there is crankcase pressure on a 1989 Volvo 740 why would there be no vacuum in the motor?

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2015-07-16 18:32:14
2015-07-16 18:32:14

If the rings are completely worn out they can put more preasure in the crankcase than the pcv can handle. Have it checked out.

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One possible cause is a blocked PCV (positive crankcase ventilation) valve. As your motor is running the crankcase will build with pressure and the PCV system will let the motor breathe. If the PCV valve is blocked or faulty then the motor will look to release the pressure somewhere else.

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your pcv valve or hose is restricted causing excessive crankcase pressure

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Plugged positive crankcase ventilation valve or collasped hose for the PCValve.

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run motor and set A/C on max, blower on full, pull a vacuum on the system and recharge with R12a 2.9Lbs

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PCV is positive crankcase ventilation

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If it's the stock motor, there is no drain plug under the crankcase. If it's aftermarket there might be a plug to drain oil from the crankcase, which would seldom if ever be necessary.

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Putting too much oil into any motor increases the pressure in the crankcase,and can blow seals and gaskets.Draining oil to suitable level is strongly advised.

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Pressure control valve controls the crank case vacuum pressure . It's important keeps ur motor from building up to much pressure an blowing out the seals

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The "470" in "R470" refers to the horsepower rating of the motor. The Volvo FH is available with a number of powerplants, up to and including the 640 horsepower Volvo motor. You'd need to specify which powerplant was in the Volvo FH.

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Volvo dealership. Have fun with that... if you've never taken off a Volvo starter, you could be in for a lot of excitement.

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it is so important because with out a motor driven vacuum it would be harder to vacuum clean also how would you clean without a vacuum cuz using a broom is hard

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Not typically as they are a 2 stroke motor

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Under the motor, tucked up inside the crankcase.

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The motor in a vacuum cleaner is an electromagnetic device.

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There is no oil in the crankcase. It is a two stroke motor. It either has an oil pump for injection or uses pre-mix fuel

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All four-stroke engines have crankcase back pressure because gases blow by the piston rings. They used to just drill a hole in the crankcase to let it out; when the government figured out this was a major source of pollution, they required the gases be captured and burned. To make this work, the hole is fitted with a one-way check valve and a hose. The hose is routed to the air intake on the carb or fuel injection. This is called "positive crankcase ventilation" (or "PCV") because the intake system's vacuum sucks the gases out of the crankcase. The valve is there for safety reasons: if the engine backfires through the carb, the PCV valve keeps your engine from exploding - which happened before the PCV system was invented. If you're getting back pressure, this system isn't working. And the problem's usually that the PCV valve is clogged or stuck shut. They should be replaced every year at the start of boating season, but since yours is clogged replace it now. If you pay $10 for one you went to a really expensive store.

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Don't take my answer for the real thing. From my understanding, those 2.0S motors (carbs) have many pressure and vacuum lines going to AND from the motor. If for any reason, there is a break in any of the lines, the motor will not function properly. in this case, when you stab the gas and hold it, the motor needs to build up pressure in order to increase RMP's. My suggestion, check your vacuum lines.

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Some of the air handling dampener motors are vacuum controlled and some have a small electric motor. If it's a vacuum controlled dampener, you probably have a vacuum leak, faulty vacuum diaphragm or disconnected vacuum line. If it's an electric dampener motor you have a bad connection, faulty feedback switch or faulty motor assembly.

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Begin by removing the positive cable from your 1990 Volvo 240 battery. Remove the cables from the front of the starter motor. Remove the starter motor retaining bolts. Reverse the process to install your new starter motor.

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I'm having the same problem. What seems to be happening with my filter system is the motor itself is more powerful than the vacuum hose can suck, the motor gets starved for water and loses pressure. I try to compensate for this by placing the 'dish-lid-thingy' (sorry I don't know the actual name) a little askew. If I can get this just right, what the motor is unable to suck thru the hose, it can also suck in thru that sliver of a gap the the skimmer box.

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The motor has to be replaced the most. Make sure you buy a high end vacuum that will last a long time. If you get a cheap vacuum the motor will burn out often and it is expensive to fix them.

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The crank case is the bottom end of the motor. This fills automatically upon running. The motor oil suggested for a Polaris 4 stroke motor is 0W-40.

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Your motor oil going bad would cause that. That is in the crankcase, not the transmission.


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