Toyota 4Runner:

95 4runner, poor power, over heats

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# 1  2/10/2011 4:19 PM

msj113
New member
Registered: 2/10/2011
Posts: 1

95 4runner, poor power, over heats

Jan/95 3.0L

Had the heads and valves done,  4 burnt exhaust valves,  2 warped intake valves. Assembled the engine on a stand,  now it heats up "too quickly" and keeps going toward the red. Radiator done at radiator shop. Water pump new.  Fan clutch new. No bubbles in radiator. Starts instantly, runs smooth, very poor power.  Ignition timing retarded 10 degrees base,  8 degrees not shorted. 

At assembly time,  cam drive sprockets may have been mixed up, timing belt marks lined up. Rolled over twice with wrench, valve timing marks still on, distributor on the correct tooth, spark plugs all lightly carbon coated,  approximately 2 hours run time. 

Catalytic Converter is kinda stinky, definitely humid exhaust. Even after full warm up at idle. 

So before I take the front covers off and recheck the valve timing, is there a way to test for a partially plugged cat?

Any suggestions are welcome,   

Thanks in advance.

Mark

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# 2  2/10/2011 9:02 PM

TechHelp2
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Registered: 11/24/2009
Posts: 1299

Re: 95 4runner, poor power, over heats

To check a catalytic converter is fairly easy. It can be done by removing an oxygen sensor and installing a back pressure gauge. You may be able to rent an exhaust back pressure gauge or fittings at your local Auto Zone store and use an old vacuum gauge to check the back pressure of the exhaust. The pressure should not exceed one pound of pressure. If it does your Cat is probably going bad or you have a blockage some where else in the exhaust.

If you have an old car that doesn't have an oxygen sensor in the exhaust then you can use a vacuum gauge. Install the gauge on any port that is manifold vacuum and not ported vacuum.

Make sure the engine vacuum is at factory specs before you proceed. Low engine vacuum can be the result of improper valve timing or retarded ignition timing.

Race the engine to 2500 RPM's and watch the vacuum. If the vacuum starts to diminish and show pressure then the exhaust probably has a restriction in it which will most likely be the catalytic converter.

If you need any more information we are here to help.

Let us know how you make out.


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# 3  2/18/2011 12:44 AM

Administrator
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Registered: 9/27/2008
Posts: 1279

Re: 95 4runner, poor power, over heats

Definitely check the cat first as TechHelp2 described. Running smooth kinda eliminates a misfire, but if testing does not show an exhaust restriction --- check the fuel pressure. A bad pump or clogged filter can limit power (smoothly) while making the engine run hot-as-heck due to the lean condition.


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# 4  2/27/2011 7:41 PM

jglenn11
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Registered: 2/27/2011
Posts: 3

Re: 95 4runner, poor power, over heats

You probably have already done this, the coolant needs to be filled using a special tool. It is a vacuum system that uses shop air with a gauge to let you know when it is vacuumed. You use the set up to fill it, the vacuum drawing the fluid into the system. I ran into this the first time I did the heads on a 3vze engine. There is an air pocket that forms at the thermostat, I was told. I have done several jobs now and never ran into the problem since using this tool.

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# 5  2/28/2011 12:51 AM

TechHelp2
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Registered: 11/24/2009
Posts: 1299

Re: 95 4runner, poor power, over heats

Yes the tool is very helpful, but most people don't have one.

If they don't have one, just raise the front of the vehicle and run the engine with the radiator cap off. The angle of the vehicle lets the air pocket work its way out. It takes a little longer but is effective.


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