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Old 03-12-2006, 07:01 PM   #1
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Default Questions About a 2.5L 4Tech Grand Am

First, I know this isnt a Bonneville question per se, but I have posted these questions in a Grand Am forum yesterday, and I am still waiting a reply. I thought I would post it here, to see if anyone here can help with this Pontiac.

First, this car has been in the family for about 2 years, and has basically sat that whole time. I would run it every so often, just to make sure things don't freeze up. It has the 2.5L 4tech motor (the so-called Iron Duke). It'* a '89 Grand Am LE, with only 96,000 on the clock.

Here are my main concerns:

- Low oil pressure. I took the car out of storage yesterday, and immediately had the oil & filter changed, since the oil was dark, and it was so old. The level was fine, and the pressure (by the gauge) was mid range until the car was really warmed up, then it dropped. I put 10W30 oil in it (GM recommended) and now the pressure is barely above the red zone, and rises only when it acclerates to 2500+ rpm. If I put thicker oil, say 20W50, will this help? Could this be a sensor, or more likely the oil pump?

- The radio will only display the time, and will do nothing else. Is there a separate fuse for the radio functions? My fusebox is not labeled, and I dont have the owners manual. Where can I find out which fuses are which, and if there is more than one fuse panel?

- My speedo is crazy! It will register the correct speed about half the time. The other times, it'* at 0, or will bounce up to the top of the scale, and back down, and back up repeatedly. Is there a sending unit that controls this (and where)? Or. am I looking at something else?

I am trying to fix this car for daily use, either to give to my son, or to sell it. Any help from the Bonneville folks would be appreciated. Thanks for your patience.

Thanks,
John
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Old 03-12-2006, 09:54 PM   #2
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I've got this same motor in my fiero, it'* a fantastic engine. Mines got about 65k miles on it, but my oil pressure also sits right at ~20 PSI when hot. It never goes below that, so i wouldn't think too much of it unless you actually get an oil pressure warning light.

Radio- The fuse for the radio would prevent any power at all. You may have a bad power switch in the unit. Do you mean by just the clock that even when you press the power button nothing happens? You may need to pull the radio and check for voltage at both the switched and constant power.

As for the speedo. Check the connections at the speed sensor on the transmission. You may have a failing speed sensor. Other than that check the connections on the gauges. Just like the bonne guys.
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Old 03-12-2006, 11:07 PM   #3
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Thanks. I heard the 4tech motor is a good one.

A couple of things: With the OEM radio, like I said the clock works, and I can even adjust the time, but I can't power up the radio.

On the oil pressure, I just went and started the car after about 4 hours of rest (60 temp outside) and the OP is holding at 40. But I didnt let it fully warm up, so we will see.

Just now when I was idling, the dpeedo bounced up to the top of the scale, then back down. I could hear gear-like movement behind the cluster??

So thats the update.

Thanks the help! Any more insight is appreciated.
John
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Old 03-12-2006, 11:19 PM   #4
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I've had really bad experiences with a 85 4tech in my old Buick Somerset. Burnt a hole straight through a piston. Got a new block and internals, did it again. Fixed again, blew a head gasket. Never moved under its own power again. Recent thoughts back to it revealed the reason for the holes. When ever I shut the car off, I'd hear a click, which I found to be the pre-heater valve on the intake that would pull air off a heatshield on the exhaust manifold. It was supposed to be open only when it was cold, but it was open all the time, pulling in extremely hot air.

In the last leg of its life, all the gauges but the speedo read twice what they should.
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