LT1944

I'm new to the LT1, and have already checked the archives, so please give me some advice.

I have a '97 LT1 that was just transplanted into my car. I am running a '95 PCM and have PCM4Less programming. The only real mods are shorty headers, LT4 KM and block sensor, CAI, 160F stat, and SVO 30#/hr injectors. I have new plugs, wires, and O2 sensors. I am running a brand new, aluminum Fluidyne radiator with a 14" puller fan. A/C is not hooked up yet.

Today, I warmed the car up by driving, and then sat at idle for about 15 minutes. The water temperature, reported by FreeScan, slowly inched up to 248 degrees! I started moving at that point so that it didn't go any higher. It came down fast when driving, and levelled at about 220F. On the highway, it is a constant 195F. I have bled, bled, and rebled the system with no real results. I have to refill the coolant pretty often, but I'm not sure if it is going out of the overflow, or if I have a blown head gasket. No chocolate milk in coolant, no white exhaust.

To add to the mystery, my BLM's are way off. One side is 128 at idle, while the other is 111. Both INTs are 128. When I am driving, they go up to 132 and 112 respectively. The O2 sensor reading 128 at idle dithers between 200 and 500mv, while the other side goes between 75 and 700mv. Why the big difference?

I am thinking about a 3000 CFM puller for the radiator, and maybe an oil cooler. I live in Florida, and its just damn hot in the summer. But will I be putting a bandaid on it without solving the real problem? Once the A/C is hooked up and running, the condenser will just add to the heat soak.

Any advice would be greatly appreciated.

joeSS97

If your fan is coming on at the proper times then I would say you need a bigger fan,maybe two speeds?What kind of vehicle is it in?

joeSS97

DOH!a 944,ok.Another possibility,maybe your radiator is too small?Not enough rows?

LT1944

The motor is in my Porsche 944 Turbo. The fan is coming on at the right temps, but I just don't think its pulls enough. I have a friend who has the exact same setup in his car, and he never gets above 210F.

I bought this motor from Speed Automotive, and its supposed to have low miles. Scott refuses to send me the VIN number or a copy of the title now though. When I replaced the injectors, 3 of them were rusted open, and the inside of the intake was full of black crud. I think the motor had been under water at one point. It started right up and runs out all right though. I just don't know what damage may have been done.

I am going to check over the water pump tomorrow and see if there are any leaks.

joeSS97

If all else fails,you could drill a few holes in the thermostat.Also might try an electric water pump.Do you know what that car weighs with that motor in it?I bet it moves out pretty good.

shoebox

From your description, it seems like the fan is not pulling enough air. If it cools when on the highway, then you would think that the radiator capacity is enough. Either that, or your water pump is not flowing very well at idle.

There is no way to use the regular dual fans?

I would like to see pics of this thing!

BigRich

yeah pics!!!

must be a smaller radiator huh?

LT1944

Oh Yeah - it moves! It weighs about 3020 lbs with spare tire and full interior. Weighs about 3200 lbs with me in it. I haven't taken it to the track yet though. I have to work out some of these bugs first.

I suspect the water pump at this point, but don't want to change it if I don't have to. I definitely don't want to go with an electric. I've just heard too many horror stories about them failing prematurely.

LT1944

Pics at:




http://www.picturetrail.com/gallery/...898&uid=129677



So, do you think that I should start with the big fan and then try the oil cooler if that doesn't help?

shoebox

Nice work.

Amazing, you can see the back of the intake.

I would not waste my time with a stock type oil cooler. They have been suspected of causing some problems.

matt diamond

I had the hardest time trying to figure out my overheating problem a while back. It turned out to be the 160* tstat. I replaced it with a 180* and now my car runs at 197* even when it is 115* outside. What was happeing was the 160* was not allowing the coolant to be in the radiator long enough for it to cool down at idle and on the street. Try to change the tstat to a 180*. I bet that will fix your problem.

LT1944

I am a bit confused now, but correct me if I'm wrong here.
Since my current tstat opens at 160*, it lets coolant into the radiator at that lower temperature. If I replace it with a 180* tstat, it will delay the circulation to the radiator until the coolant reaches 180*. Neither tstat has any bearing on the velocity at which the coolant flows. That is the job of the water pump. So unless your 160* tstat was bad, I don't understand how the 180* tstat alone would have helped your overheating. The coolant would be passing through the radiator at the same
speed once each tstat opened. Let me know what I'm missing here.

Wild1

That radiator looks like it's 16 - 18 inches. May not be enough. Can you calculate the surface area in square inches and compare it to the stock radiator?

LT1944

I'll have to get my measuring tape out tomorrow and see what the dimensions are. Like I said, though, my friend is running the same exact setup with no problems at all.

Also, no one has answered my questions about why my BLMs are so different on each side of the motor. Do I have a vacuum leak of some kind?

Wild1

Lop-sided BLMs can indicate an intake vacuum leak, Bad O2s, or an exhaust leak at the header flanges near the O2s. Also, an O2 wire could have been smashed (lose insulation/short to ground), melted, or bad connectors.