Post was last edited on May 13, 2009 05:05. This post has been edited 1
times.
Post was last edited on May 13, 2009 05:05. This post has been edited 1
times.
roger1918
+1y
Here are the answers to your questions:
What temperature is your thermostat now? 180 degrees. It had a 195 in it which seemed to be working OK when I checked it in hot water although I didn't have a thermometer to check it with. It opened fully just as the water started to boil.
Is your truck an auto or manual? Manual.
How sure are you that the radiator isn't stopped up with corrosion or other materials? Pretty sure. I had the radiator core cleaned out a few years ago because it was running hot according to the dash thermometer. Now it runs cool.
Is the fan clutch working properly; do you know? All I know is it runs cool even steady at almost full throttle in 5th on the freeway. The fan turns freely with the engine stopped.
Do you have a/c? Nope.
What condition is the radiator cap? Good. It's pretty new.
If you have achieved closed loop at various engine speeds, it is time to move to the ob NOX tious part of your emission issues.
I took it out for a longer drive today with the dwell meter hooked up. If it is pulling at all it wants to be at zero dwell. Pulling at a steady 55mph in 5th gear gives 2400 rpm with my gearing. Dwell sits at zero. Accelerate: zero. Take foot off gas: dwell starts climbing into teens. Come to a stop at a light and the dwell starts climbing in about 15 seconds to the 40 to 50 range.
At a steady 30 mph in a gear that gives around 2000 rpm the engine is loafing and the dwell jumps around in the low teens or less.
I never saw it go out of closed loop while driving. Back at my garage with the engine idling I did see it go to 27 degrees once. I goosed the rpm a bit and it went back into closed loop and stayed there at 40 to 50 degrees.
Post was last edited on May 13, 2009 05:05. This post has been edited 1
times.
roger1918
+1y
OK, I will try to find one.
Edit: I have ordered a 160 degree thermostat which will be in this afternoon. I sampled a new fan clutch and it does have more resistance to turning even when cold (and I assume much more when hot).
Post was last edited on May 13, 2009 05:05. This post has been edited 1
times.
roger1918
+1y
I checked the clearances and set the intakes at 0.013" instead of 0.012". It didn't make any difference on a compression test, but I didn't expect that it would because the rpm is so slow the cylinder will fill up even if the valve opens a bit late. I needed to do a valve check anyway.
Post was last edited on May 13, 2009 05:05. This post has been edited 1
times.
Post was last edited on May 13, 2009 05:05. This post has been edited 1
times.
roger1918
+1y
I did post a reply to you a couple of days ago - at least I thought I did. Apparently it didn't "take". So trying again.
I don't have access to an infrared sensor. However, I don't think the engine is running hot. With each thermostat change the temp gage on the dash has been showing lower and lower running temps. With the 160 degree unit in there the temp gage stays almost at the bottom of the scale.
Re: the cats. The rear one was a plain vanilla aftermarket replacement unit I got on the internet. The front one is supposedly California approved OBDII compliant unit.
Ever since I adjusted the valves and changed the thermostat to a 160, the ECU has been dropping out of closed loop after 15~20 seconds. I know the mixture solonoid is working OK because when the dwell goes from 0 to 27, the idle rpm drops by over 100 rpm.
I checked the temp switch and thermo sensor resistance and they aren't the problem. It was behaving like the O2 sensor isn't working so I put a voltmeter on the O2 sensor. I am getting 0.0 volts at idle no matter how I vary the mixture screw (and I can tell the mixture is changing like it should). But if I blip the throttle to inject a bit of fuel the O2 sensor voltage jumps up to 0.7~0.9 volts, so it isn't dead.
I gues I will try my old O2 sensor next.