95z28 fans stay on at cold start and overheating - CamaroZ28.Com Message Board


LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Like Tree7Likes
Reply
 
Thread Tools Search this Thread
Old 03-02-2015, 04:30 PM   #1  
Registered User
Thread Starter
 
Join Date: Mar 2015
Location: Bay Area California
Posts: 13
95z28 fans stay on at cold start and overheating

Hi , I hope I am posting this in the right place.
I am a newbie who just sold my g35 6mt (bad head gasket ...) and bought a 95z 28 Camaro AT.
I bought it from the original owner. The car is really clean. The car had a huge overhaul done on it when the engine was replaced a year and a half ago. The car has a Jasper Remanufactured engine in it with only about 8k miles on it. The radiator, water pump and hoses, belts ect were also replaced at that time. the chassis and auto tranny has 166k on it.

When I went to go look at the car, as soon as they brought it out from a cold start the fans were on. I questioned this to the mechanic as the car was female owned and she was having the car shown at her mechanics shop by the mechanic himself.He said they were like that for awhile and didn't know what the problem was. My bf (who is an auto tech) and I drove it and played with it trying to get it to either overheat or get the fans to come off and had no luck with either. Transmission also shifted pretty good.

No check engine or any other dash lights on. Other than the fans and worn front brakes, the car seemed as flawless as i could expect for a 20yr old chevy.

I bought it, drove it work fine (20 miles). Then when I was off I drove it home (10 miles) and as soon as i pulled up in front of my house the temp gauge was all the way to the red and after i shut it off a bunch of coolant poured out of the bottom of it.
sigh fml...

Anyway, towed it to my shop and they found the water pump to be leaking and a radiator hose. They also said something about a temp sensor.
My mechanic also said that it felt like the engine was not running on all 8 cylinders. There appears to be an oil leak. not sure if its just from the drain plug or the main seal.

they have had the car since the day after I bought it. Its been 5 days and still not done.

Does anyone have any thoughts on why the fans were on and stayed on from a cold start?
Do you think they were related to the water pump and hose leak or 2 separate issues?

And last, does anyone have an experience with jasper reman. engines? Im not finding a whole lot about them and what I have found are mostly complaints.

Thanks so much
Magenta_Hearts is offline   Reply With Quote
Old 03-02-2015, 04:49 PM   #2  
Super Moderator
 
Injuneer's Avatar
 
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 66,271
Re: 95z28 fans stay on at cold start and overheating

As mentioned in you "new member" thread, the fans running at cold start could be:

1 - The PCM has set a DTC that causes the fans to run at cold start. You indicate the SES light is not on. Does the SES light come on for a few seconds when you turn the key to "run", to verify that the bulb is not burned out or "removed" to cover up a problem? A failed coolant temp sensor is typical of a trouble code that would cause the fans to run all the time. The most frequent cause is a blown fuse for the AIR pump.

2 - Someone could have wired the fans to run all the time, which is not a good idea, or they may have added a thermostatically controlled switch or a manual switch. Again, this might have been done in an attempt to cover up the overheating problem.

The PCM with stock programming would turn the fans on low speed at 226*F, and go to high speed at 235*F.

The fans will not come on due to a problem with the water pump, or a leaking coolant hose, unless the problem or leak causes the coolant temp to exceed 226*F.

Also, if the coolant system lost enough coolant to cause the system to overheat, the "Low Coolant" light on the dashboard should have come on. Another problem light that is easy to defeat, simply by unplugging the coolant level switch on the passenger end tank of the radiator.

Check the coolant level switch to see if it is connected:

http://shbox.com/1/low_coolant.jpg
Injuneer is offline   Reply With Quote
Old 03-02-2015, 05:04 PM   #3  
Registered User
Thread Starter
 
Join Date: Mar 2015
Location: Bay Area California
Posts: 13
Re: 95z28 fans stay on at cold start and overheating

The picture is so helpful ! thanks. I know alot of stuff but I am still no mechanic and some things I know alot about and others I dont so pics are great.
Im gonna send the pic to my bf who works at the shop and see whats up.
Magenta_Hearts is offline   Reply With Quote
Old 03-02-2015, 08:52 PM   #4  
Registered User
 
ACE1252's Avatar
 
Join Date: Mar 1999
Location: Kernersville, NC
Posts: 1,944
Re: 95z28 fans stay on at cold start and overheating

As Injuneer mentioned, the fans coming on and staying on are not normal. It may also be a problem with the AC system. High pressure in the AC system will cause the fans to go wide open as well. I know this from using my AC pressure sensor input port to log wideband O2 information through the LT1 PCM.

The fans itself is enough to raise an eyebrow, but for it to actually overheat is not good. Could still be something simple as someone not knowing how to properly fill the LT1 reverse flow cooling system and the system was not full...but the reason why it overheated needs to be found and then any fallout from the overheating itself dealt with(warped heads/block/etc...if it got hot enough).

Make your tech knows how to properly fill and bleed the LT1 coolant system. Don't overbleed it....can actually introduce air into the system under the right conditions....follow the GM manual to the letter....the bleed valves are only for filling the system and no more....do not open when running. See my post here...
https://www.camaroz28.com/forums/lt1...needed-819889/

I'm not sure if installing the wrong type thermostat will cause overheating, but the LT1 does not use a conventional SBC thermostat. Just another gotcha to look into....
http://shbox.com/1/tstat.jpg

I overheated my LT1(temp pegged at 260*) when the AIR pump fuse blew(cooling fans are on the same circuit in a '96) and the fans didn't turn on when commanded at idle. I was sitting in the car looking up the AIR pump code, with the engine running, when I smelled coolant and then heard boiling.

It ended up warping both my heads by ~0.003 each. Enough to give me head gasket and cooling problems(showed up as cooling issues afterwards....temperature moving around during steady state cruise on the highway @ 60mph). Normally during 60mph the temp was rock solid around 190*, but after the overheat when crusing @60 it would go up past 210*, back down to 190*, back up to 210*, and move around really strangely. The only time the coolant temp should move around is when the car is at idle. 190* then up to around 220ish, then back down to 190ish as the fans cycle on and off(on a stock LT1).

I've learned enough now to work on my LT1 myself(so only I touch it), but back then I didn't know enough. I found a really good GM tech in Danville, VA(Robert Woodall Chevy...not sure if he is still there...). He figured out my problem and showed me the head gaskets. You could see where the coolant was moving back and forth between coolant passages on each head(leaking and such). I'm very thankful for having him to work on my Z28 at that time. He really knew what he was doing.

Hopefully, you got it turned off sooner than me and will not have any head issues to deal with.
94Z28LS1toLT1 likes this.

Last edited by ACE1252; 03-03-2015 at 12:20 AM.
ACE1252 is offline   Reply With Quote
Old 03-03-2015, 12:13 AM   #5  
Registered User
 
dark-evader's Avatar
 
Join Date: Mar 2014
Location: Orlando
Posts: 42
Re: 95z28 fans stay on at cold start and overheating

my fans were hardwired to stay on which i prefer, cause i drive like I'm in nascar, some mechanics just cannot operate on the lt1 and make things worse, its best to find mechanics that have the experience with that engine.
dark-evader is offline   Reply With Quote
Old 03-10-2015, 08:29 PM   #6  
Registered User
Thread Starter
 
Join Date: Mar 2015
Location: Bay Area California
Posts: 13
Re: 95z28 fans stay on at cold start and overheating

Turns out my check engine light was burnt out... fml
Was an air pump(?) and a leaking water pump.
Magenta_Hearts is offline   Reply With Quote
Old 03-10-2015, 09:47 PM   #7  
Member
 
GaryDoug's Avatar
 
Join Date: Jul 2010
Location: Florida West Coast
Posts: 1,129
Re: 95z28 fans stay on at cold start and overheating

Did you notice that was item #1 of things to check in Fred's response?
Injuneer likes this.
GaryDoug is offline   Reply With Quote
Old 03-14-2015, 11:36 AM   #8  
Registered User
Thread Starter
 
Join Date: Mar 2015
Location: Bay Area California
Posts: 13
Re: 95z28 fans stay on at cold start and overheating

Quote:
Originally Posted by GaryDoug View Post
Did you notice that was item #1 of things to check in Fred's response?
umm yeah lol thats how we figured it out was from the suggestion. Turned the key over and the ses light did not illuminate so hooked it up to a reader and there were the codes.
I always seem to have the worst luck in life in general and especially when it comes to cars.
Thanks so much for the help!
Magenta_Hearts is offline   Reply With Quote
Old 03-14-2015, 11:49 AM   #9  
Super Moderator
 
Injuneer's Avatar
 
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 66,271
Re: 95z28 fans stay on at cold start and overheating

Wow.... you mean I actually got one right?
bw_hunter and 94Z28LS1toLT1 like this.
Injuneer is offline   Reply With Quote
Old 03-16-2015, 11:47 PM   #10  
Registered User
Thread Starter
 
Join Date: Mar 2015
Location: Bay Area California
Posts: 13
Re: 95z28 fans stay on at cold start and overheating

Yes Lol
Magenta_Hearts is offline   Reply With Quote
Old 03-28-2017, 11:03 AM   #11  
Registered User
 
rmanz28's Avatar
 
Join Date: Oct 2016
Posts: 9
Re: 95z28 fans stay on at cold start and overheating

hello...saw your post on fan always running and start up....mine has been also can seem to figure out why, anyway..i have other issues going on and was wondering what typ of code reader you used, I can seem to find one that will connect to my 95 z28
thanks for your help
rmanz28 is offline   Reply With Quote
Old 03-28-2017, 06:39 PM   #12  
Registered User
 
gaedbo's Avatar
 
Join Date: Dec 2015
Location: St. Paul, MN
Posts: 193
Re: 95z28 fans stay on at cold start and overheating

Quote:
Originally Posted by rmanz28 View Post
hello...saw your post on fan always running and start up....mine has been also can seem to figure out why, anyway..i have other issues going on and was wondering what typ of code reader you used, I can seem to find one that will connect to my 95 z28
thanks for your help

Maybe you will want to try the Free SCAN 93/94/95 software created by Gary Doug. It would give you specifics that could be analyzed, and possibly lead you to the correct solution.

Click on the link below !

https://www.camaroz28.com/forums/com...95-lt1-874306/

READ the information before you download it so you will know which download to select, and how it works.

You will need a cable and a laptop to use it. One of the places you can get a cable from is OBD Diagnostics

You can also make your own cable, the instructions are in the Scan link created by Gary Doug.

Injuneer the Super Moderator is able to read and diagnose the file if needed.
Fatdog2 likes this.
gaedbo is offline   Reply With Quote
Old 03-29-2017, 08:18 AM   #13  
Registered User
 
rmanz28's Avatar
 
Join Date: Oct 2016
Posts: 9
Re: 95z28 fans stay on at cold start and overheating

thanks for the link.....I hope I can get it working. also ive been having opti issues now I think, had it replaced last fall, ran pretty well before I put it up for the winter. now it wont start. it had some rumbles but nothing.....most rumbles are when I let off the key....any ideas?......I see your from St Paul...GO VIKINGS!!!...im a huge fan!
rmanz28 is offline   Reply With Quote
Old 03-29-2017, 12:25 PM   #14  
Super Moderator
 
Injuneer's Avatar
 
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 66,271
Re: 95z28 fans stay on at cold start and overheating

Scan9495 will pull the codes, and as noted, can produce a detailed scan log of the engine while operating. For a quick access to the codes, you can an OBD-1 scanner with a 12-pin --> 16-pin adapter, or use Shoebox's "jumper" photo:

http://shbox.com/1/xraycable.jpg

If you can find an old Auto Xray scanner, it will work. Ignore the $30 Actron, because all it does is short the pins in the ALDL connector, and that won't work after 93. Actron makes a dual OBD-1/OBD-2 scanner that is highly discounted because there is an upgraded model.... CP9185 Elite. As low as $74 on Amazon. Do not buy an Equus or Innova dual scanner - the internal database for the LT1 is corrupt, and it it will give you seven false codes.

Have you checked the fuel pressure? Have you checked for spark at the plugs? When the starter cranks the engine, does the tach needle move up a couple hundred RPM?
Injuneer is offline   Reply With Quote
Old 03-29-2017, 02:26 PM   #15  
Registered User
 
rmanz28's Avatar
 
Join Date: Oct 2016
Posts: 9
Re: 95z28 fans stay on at cold start and overheating

my bad, it is a 95 z28 LT1, 118,xxx miles, ive had it for almost 6 yrs...as far as I know the engine is stock, I believe the exhaust is upgraded by the sound. it has run fine up until last year and no spark was the culprit. I just bought a spark tester, will try to chk that soon....the fan turning on with the key has me stumped tho..its not suppose to do that...I can here the fuel pump, but am pretty sure its getting gas....I smell gas when trying to start it (new pump 3 yrs ago)
appreiciate all your advice
rmanz28 is offline   Reply With Quote
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Throttle response not as crisp when warm? 94Form LT1 Based Engine Tech 10 02-10-2015 11:23 PM
multiple codes point to alternator <8 at idle, bad alternator? Gtpguy General 1967-2002 F-Body Tech 48 01-26-2015 04:50 PM
It's COLD. Get WARM. Save 10%. Heated Seat Kits on sale @ PFYC-PartsForYourCar PFYC Supporting Vendor Group Purchases and Sales 0 01-23-2015 01:13 PM
Car starts then dies immediately Oncomingstorm22 General 1967-2002 F-Body Tech 4 01-22-2015 07:15 PM
ABS INOP TCS OFF and Air Bag lights on squarehead General 1967-2002 F-Body Tech 7 01-15-2015 07:02 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 02:13 AM.


Copyright © 1996-2017 CamaroZ28.com. All rights reserved.
We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.