Another FNG............
Thread Starter
Advanced
Joined: Apr 2007
Posts: 66
Likes: 0
From: So. Orange Co. Ca.
Another FNG............
....with his 1st post. Hello to all! Recently returned to the Coirvette world after a looooong absence. Had a '69 that I sold years ago & have been sorry ever since. This beast is a whole different thing - but I'm lovin' it! A '94 LT1 w180k, but overall in good shape. Have a few issues I would like to pick your brains about, if I may:
Auto HVAC system: Can't seem to get the heater to work - A/C is cold & temp buttons work, but no heat. Control box? Heater valve? Is there a way to trouble-shoot the system?
Tachometer: Either I have the slowest reving 5.7 in the world, or the tach is off. Idles at 5k - shows about 1400k at 65mph. Is this normally an internal tach problem or more likle the sensor? (of course, if it's normal, then my engine should last forever!
Coolant temp: Running about 210-215 at speeds. I think that's a little high - thermostat and system flush?
Thanks in advance
Auto HVAC system: Can't seem to get the heater to work - A/C is cold & temp buttons work, but no heat. Control box? Heater valve? Is there a way to trouble-shoot the system?
Tachometer: Either I have the slowest reving 5.7 in the world, or the tach is off. Idles at 5k - shows about 1400k at 65mph. Is this normally an internal tach problem or more likle the sensor? (of course, if it's normal, then my engine should last forever!
Coolant temp: Running about 210-215 at speeds. I think that's a little high - thermostat and system flush?
Thanks in advance
Burning Brakes
Joined: Apr 2007
Posts: 759
Likes: 0
I have a 94 too. Just went thru the same thing on mine...1st. have the cooling system back flushed. This cured the problem you are experiencing. (just got it back yesterday from the shop). My engine is very low reving too. I don't think it's the tach. Change thermostat to a 185. Fans kick in at about 227. But while running I'm at about 190.
Burning Brakes
Joined: Aug 2005
Posts: 779
Likes: 10
From: O'Fallon MO
2016 C4 of the Year Finalist
2015 C4 of the Year Finalist
Tachometer: Either I have the slowest reving 5.7 in the world, or the tach is off. Idles at 5k - shows about 1400k at 65mph. Is this normally an internal tach problem or more likle the sensor? (of course, if it's normal, then my engine should last forever!
Coolant temp: Running about 210-215 at speeds. I think that's a little high - thermostat and system flush?
Coolant temp: Running about 210-215 at speeds. I think that's a little high - thermostat and system flush?
Manual or automatic? My 6 speed runs at 1500 rpm at 70 mphin 6th gear (normal)
High temp is normal as suggested swap to 160 to 180 thermostat to keep the temp down.
Enjoy
Safety Car
Joined: Jun 1999
Posts: 3,641
Likes: 2
From: Southern California
Try checking your radiator for leaves and such. You will get great results from removing the radiator and cleaning the debris out from the fins.
The LT1 idles that low. And if you have an auto with 2.59 gears your freeway rpms are spot on.
Congrats on the Vette.
The LT1 idles that low. And if you have an auto with 2.59 gears your freeway rpms are spot on.
Congrats on the Vette.
Thread Starter
Advanced
Joined: Apr 2007
Posts: 66
Likes: 0
From: So. Orange Co. Ca.
Thanx, guys...I think some cooling system PM is in order. That's weird about the tach.....I'm used to seeing 2200-2400 RPM at speed on my CTS, but if it's normal - that's cool!
Wassup with the heater, tho? Read a few posts and it seems a vaccum control valve under the fuel rail may be a suspect...thoughts?
TIA
Wassup with the heater, tho? Read a few posts and it seems a vaccum control valve under the fuel rail may be a suspect...thoughts?
TIA
Instructor
Joined: Apr 2007
Posts: 105
Likes: 0
From: FL
Take a good look at the heater hose that goes from the engine to the heater core. Believe it or not, it has a restrictor inside there. It is about an inch and a half long and is located directly under the big return ac line at the evap case. it has spring type clamps on both sides. The hole inside that thing is really only about 1/8", about as big as a pencil. All it takes is one little peice of junk and boom, no heat. I had the same problem on both cars when I bought them. Take it out, clean it, refill and enjoy! I'm no expert, I just pretend to be one on this forum 
Last edited by zapitbullseye; Apr 21, 2007 at 06:25 PM.
Safety Car
Joined: Jun 2004
Posts: 4,652
Likes: 80
From: Lakeland Florida
Hello and welcome.
For the RPMs,...that may be normal. I have an 86 and it will usually cruise at 65 - 70 around 1500 rpm.
For the temp, it will run at 220. It really had me worried at first, but after some searching on the forum I saw that this was normal.
I have owned it for over 3 years with no problems...except a transmission rebuild. The car has over 150,000 miles and is still a good running C4 vette.
kdf
For the RPMs,...that may be normal. I have an 86 and it will usually cruise at 65 - 70 around 1500 rpm.
For the temp, it will run at 220. It really had me worried at first, but after some searching on the forum I saw that this was normal.
I have owned it for over 3 years with no problems...except a transmission rebuild. The car has over 150,000 miles and is still a good running C4 vette.
kdf
Cool Hand Luke of W MI
Joined: May 2006
Posts: 5,292
Likes: 181
From: Winona Lake, IN
Welcome to the CF! I have a LT1 also, and at 80 mph in 6th gear, I am turning about 1,800 rpm.
I agree with your wanting to put the lower temp thermostat in but I give you a fair warning- that is one touchy subject on this forum, so bring your flame suit and prepare to get lit up! Use the search function on thermostat changing and see all of the threads on that topic!
Good luck with the C4, post some pics of her when you get time!
I agree with your wanting to put the lower temp thermostat in but I give you a fair warning- that is one touchy subject on this forum, so bring your flame suit and prepare to get lit up! Use the search function on thermostat changing and see all of the threads on that topic!
Good luck with the C4, post some pics of her when you get time!
Last edited by wmupaprmkr; Apr 22, 2007 at 11:34 AM. Reason: i type like a idiot
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Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
Coolant Temp: normal range, no need to change anything, might want to do search function and see about cleaning out in front of rad, as the c4 does act as vacume cleaner for junk.
Tach: sound about normal....
Tach: sound about normal....
