considering buying a 1997 park ave. ultra

[rtm1165]

i found this 1997 park ave ultra with 186000 ,miles on it ,, the car appears to run good the only problem in have with it is that it appears to run a bit warm,,

the temp hand is just above halfway,,,

,the raiditaor was also leaking but the dealer is replacing it.

my question is,, where should the temp hand be??? 3/4 or 1/2 or what????

i know i cant buy the car and allow it to run consitently warm, is this a real concern or what???

what other reasons would it run warm??? (water pump? thermosat?
or the dreaded gasket leak???

just fyi the coolant checked out full both days i drove it.

i need some with some REAL ADVICE!!!!!THANKS MURCH

[HotZ28]

Welcome to AF! It is a pleasure to have another "Ultra" member here!

After I replaced the radiator on my Ultra, the temperature dropped about 20 deg from where it was. It never ran hot before, however it did approach 210 several times when the ambient was 95+ back during the summer. With the efficiency of a new radiator, the car should run around the thermostat set point, or slightly above. Most have a 195 deg thermostat; I use a 180 deg in the summer and 195 deg in the winter. I know it defies logic; however, it does run cooler in the summer with the 180 deg stat. I guess it depends on air circulation and cooling system efficiency.

BTW: If the radiator develops a leak, more than likely air will be introduced into the system and with air in the system it will run hotter! It is very important to bleed all the air out of the system, after any type of cooling system service! There is a bleed valve on the thermostat housing for that purpose. I am sure that the dealer knows the procedure.

On a high mileage car, the water pump could give a problem at anytime. The signs of water pump failure are, noise from the front bearing, or leaking from the weep hole at the bottom of the pump. If you could get the dealer to put a new water pump on while they are doing the radiator replacement, (even if you have to pay extra for it) it would be a worthwhile investment! If nothing else, simply for the peace of mind you would have with a new pump!

Don’t worry about the UIM failure on the Ultra, it has an aluminum intake and is exempt from that dreaded failure!

Good Luck!

[HondaManDan]

My 95' always runs about 120 deg. It NEVER reaches 200, ever. Even if I let it sit in the sun at idle.

Check the thermostat.

Dan

[HotZ28]

Originally Posted by HondaManDan

My 95' always runs about 120 deg. It NEVER reaches 200, ever. Even if I let it sit in the sun at idle.

Check the thermostat.

Dan

Dan, your post reminds me of the false sense of security I developed, when I first purchased my Ultra about six years ago. The gage never went above 120-130 deg even in the summer! I thought, wow, this is the “coolest” running car I have ever owned. I continued to believe that the gage was indicating the actual temp until my water pump developed a leak. I lost coolant and never saw the leak. One hot summer day, after the reservoir coolant had depleted and air was introduced into the cooling system, the coolant started to boil over into the reservoir after I shut the engine off. The gage did climb up to 180 deg, so I wondered, how in the hell this thing could be boiling over at 180 deg! I then hooked up the scanner and found the actual engine temp was at 260 deg! About that time, I remembered that the coolant sensor for the gage and the sensor for the CTS used to monitor engine temp for the PCM, were separate sensors! Oh well, no damage done! All I had to do was replace the water pump and sending unit for the gage.

Keep this in mind; if your car were actually running 120-130 deg all the time, it would not go into closed loop! (Bad thing)! The threshold for open loop/closed loop operation is somewhere around 140-150 deg. If your thermostat is original, the set point is 195 deg. In addition, the thermostat will not fully open, or allow full circulation until it reaches the set point. Both coolant temperature sensors, are located on the manifold and should measure actual coolant temp inside the engine, not after it flows through the thermostat. A normal operating thermostat (195 deg) will begin to open slightly @ about 170-180 deg. I would say; you either have a funky gage, or the sensor for the gage is not indicating the actual temperature! Have you checked your thermostat?

[Bassasasin]

Right on.. on the Closed Loop thing.. except for its the O2 sensor.. (exhaust) temp that I think senses part of that decision..
OTHERWISE. My park ultra 94 just got a new thermostat.. (seal and gasket). changed the indicator from 130 to 180.. 200 is about center on the meter. Got 27mpg before the thermostat change and 27mpg after.. Oh well.

Good Luck.

[Luke.]

Fm ot Z 28

A normal operating thermostat (195 deg) will begin to open slightly @ about 170-180 deg.

Now that's interesting; A new piece of knowledge. Thank you. >

[HotZ28]

Originally Posted by Bassasasin

Right on.. on the Closed Loop thing.. except for its the O2 sensor.. (exhaust) temp that I think senses part of that decision..
OTHERWISE. My park ultra 94 just got a new thermostat.. (seal and gasket). changed the indicator from 130 to 180.. 200 is about center on the meter. Got 27mpg before the thermostat change and 27mpg after.. Oh well.

Good Luck.

You are right Bass, both the coolant sensor and the 02-sensor temperature thresholds, must be met inorder for the PCM to switch over to closed loop. Once closed loop takes control, the 02 provides feedback about the fuel mixture to the PCM, and that feedback is used to constantly adjust and fine-tune the air/fuel ratio. The early design single wire 02, would normally take longer to reach the threshold temperature than the engine coolant, so closed loop operation was somewhat delayed, until the 02 reached its threshold temperature.

The newer design, “heated 02” (4-wire), has a self-contained heating element that preheats the sensor once the engine is started, thereby reducing the amount of time required for the control to go into closed loop. This means that the PCM is adjusting your fuel curve based on the sensor feedback, not the maps. I have replaced several single wire 02 sensors, with the 4-wire heated sensors and when monitored on a scanner, the time required to go closed loop was significantly reduced. (Usually within 2-minutes from a cold start)!

As previously discussed, the coolant temp sensor monitors engine temperature. The PCM uses this information to regulate a wide variety of ignition, fuel and emission control functions. For example, when the engine is cold, the fuel mixture needs to be richer to improve drivability. Once the engine reaches the threshold temperature (140-160), the PCM then switches to closed loop, and starts using the signal from the O2 sensor to vary the fuel mixture.
Happy New Year!

[Bassasasin]

Good info there.. I just remembered when I didnt like the sound of the engine when I drove off with it yesterday... Kindof rough.. but then remembered the closed loop thing..

My new Thermostat.. was stamped 175.. and my old one has the same markings..
also of note.. my thermostat doesnt cross to a Park Ultra.. it crosses over to Non Supercharged. It took several trips to the ol' Store to get all the parts right and good.

H A P P Y . N E W . Y E A R

to you all too.. (boy does that date this post) 9pm 12/31

Bass

[rtm1165]

thanks for all of the opinons men,,,now what grade of gas is the best to run in the 3800 seris 2 with the supercharger??