1998 Camaro Z/28 Ls1 Overheating

**rolyan76** · 11-13-2006, 09:04 PM

I have a 1998 Z/28 with alot of bolt ons, see list below. About a month ago the PCM started throwing out P017 & P0174, Fuel Trim Lean Bank 1 & 2. I checked for vacuum leaks with carb spray, in common leak areas, replaced O2's, replaced PCV Valve. I cleared the code and all was good untill I would get on it. The SES light would come on. I disconnected the battery and reset the PCM, and the light hasn't come back on. Then about a week ago, I opened her up on the freeway, like 140MPH. As I started slowing dow, I noticed the temp gauge rising. Just before red zone, I pulled over and let her cool down. any way I got her home, and she has 125,000 miles, so I thought it's gotta be either water pump, or thermostat. I went with the Meziere Electric pump, and new therm. I figured it was all good. Took her out, and she overheated, and blew the radiator. Pump is working great, therm is brand new,and everything is installed correctly. I replaced the radiator with a Be Cool and thought, no more problems. Sure enough, she still gets way too hot. The only other thing I can think of is that the LS1 is still running lean, (with no codes?), possibly clogged cat and/or cat's.
I ordered new cat's but what do you all think.With all the airflow coming in, it makes sense that it is running lean, but I just don't know. I would appreciate any help, for I am out of Ideals. Oh yeah I also just order a Ractronix fuel pump, but I have hooked a fuel pressure gauge up to the fuel rails and I've got good 60 PSI witch drops a little (58 PSI) under load. Could this also be a bad regulator???

1998 Camaro Z/28 Mods.
1. SLP Air Lid
2. SLP MAF Sensor
3. SLP Air Bellow
4. SLP TCM ASR Reversal Module
5. SLP Fan Over Ride Switch/Harness
6. SLP Hurst Shifter Ball
7. SLP Cold Air Induction (Not Installed)
8. SLP Strut Tower Brace
9. F.A.S.T. 78mm Billet Throttle Body
10. EGR Tube Cut
11. ASR Underdrive Pulley set with Alternator Pulley
12. Meziere Electric Water Pump
13. Be Cool Aluminum Radiator
14. K&N Air Filter
15. Flowmaster
16. Mindon 160 degree Thermostat
17. Racetronix Electric 255 lph Fuel Pump w/ separate 12v line (NOT YET)
18. MSD Coil Packs
19. MSD Wires
20. NGK Iridium Plugs
21. ZO6 Clutch
22. Eibach Pro Springs
23. Edelbrock Torque Arm
24. Edelbrock Pannhard Bar
25. Bilstein Shocks
26. Superior Rear Axles
27. 17” SS Grey Rims
28. Skip Shift Eliminator

Parts Replaced (125,000)
1. Rear Axle Seals
2. Rear Pinion Seal
3. Clutch Slave Cylinder
4. Rear Brake Pads (Carbon Fiber Composite)
5. Oxygen Sensors (Bosch)
6. PCV Valve
7. Radiator Hoses
8. GM Corvette LS1 Water Pump Gaskets

**SeVeReDiStOrTiOn** · 11-13-2006, 10:36 PM

Put the stock maf back in....do a good coolant flush. You might have some old dex clogging shit up...also check all hoses(upper, lower, heater) and make sure none are collapsed. I'm sure you know all this but make sure you bleed the air out really good.

**Hot Black Trans-Am** · 11-13-2006, 10:42 PM

I'm thinking cats. when it's getting hot pop the hood and check to see if the manifolds are glowing. (works best at night)

**markgaydos** · 11-14-2006, 07:47 PM

I have a '98 Z with 111,000 and just started having the same problem two days ago. Temp shot up to 265 and before that no problems at all. Both fans are working, flushed the radiator, but the temp is still shooitng up after 20 minutes of driving. Going into the shop tomorrow to replace the thermostat to start.

I have minimal mods.

MG

**rolyan76** · 11-14-2006, 09:23 PM

Thanks for everyones input. Let me know if the thermostat helps. Thanks again, and if anyone else can help, please do.

**rolyan76** · 11-15-2006, 02:18 PM

Are you kidding me? Bad radiator cap. This shit has been plagueing me. Thanks for all the help guy's.

**sunsetorangess** · 11-15-2006, 02:31 PM

Glad you figured it out....
J

**2001NBMZ28** · 11-15-2006, 02:38 PM

Bad radiator cap won't hold pressure for sure - it's not overheating now after replacing it?

**rolyan76** · 11-16-2006, 05:56 PM

No overheating. Apparently when the coolant expanded, it couln't excape into the overflow bottle because the cap prevented it from doing so. In turn super pressurizing the water, i guess causing it to boil. Cap spring was stuck down.

**sscamaro1384** · 03-05-2007, 10:00 PM

i recently replaced my water pump and tstat and that solved my cooling problems but now i have a lopey idle at a stop light. sounds like it will cut off but doesn't. codes say bank 1 and 2 lean. maybe i need new o2 sensors but what r the chances of both going out at the same time. what could have caused this? would o2 simulators work instead of replacing the o2s if they are bad? can' t figure it out. please help.

**Rivi** · 03-08-2007, 03:07 PM

Originally Posted by rolyan76

No overheating. Apparently when the coolant expanded, it couln't excape into the overflow bottle because the cap prevented it from doing so. In turn super pressurizing the water, i guess causing it to boil. Cap spring was stuck down.

sorry but its just the opposite,the higher the pressure the higher the boiling point.a bad cap lets the pressure excape causing the coolant in the rad and engine to boil.boiling coolant is useless so the engine overheats.replacing the cap helped because now its holding full pressure on the system.if the cap was "stuck" so it couldn't open at all it would blow a hose off etc.signs of a bad cap are overheating under a heavy load where otherwise the temp seems normal.