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Hello everyone! Hope everyones favorite/baby - fbody is running fast & strong. I just wanted to take a minute to vent my frustrations and allow a moment for anyone to throw in a little insight. There are so many forums these days (with facebook car groups getting so popular) and with that your normal less than experienced 2 cents/point of views from so many "enthusiasts" so I thought I would bring this post here.
Long story short - my current fbody (95 Z28 Vert A4) I picked up in 2015 has been ever so bothersome to me with it's cooling issues. I think in the past 2, going on 3 years - I'm on my third water pump and 3rd radiator. Not sure about thermostats and I'm on my second set of hoses.. (First set of each are what came on the car)... Original issues had me replace everything (went with OEM replacements) ACdelco pump, hose kit, radiator - that was like my first " MOD" to my car was cooling work.. Did alright.. then 8-9 months later more issues... So I replaced the pump this time.. Then.. Had another issue that led to a head gasket failure.. SO i was just sick of this motor and I had plans of a bigger, better, faster motor so I had a 383 built for me that i've plain grown to love.. Had a lil hot temps running up, So I replaced the stock rad with a 3core aluminum tig "Direct Replacement" - Threw on a new water pump - I was also having issues with the factory temperature gauge that I had to do some tinkering with to get it to work again.. It was plainly just inaccurate and at this point I feel like I got this cooling down to a science so I even have a analog gauge installed that just hangs out on my floor board. So anyways, 7,500 miles on the new motor, I think 3k miles since the 3core was installed I was driving along last night and the temperature crept up to 235 degrees - maybe 238, and then came back down to about 225.. Now I know the operating temps, I've heard about what "Johnny that installed a 160 stat, reprogrammed his fans to come on earlier etc and never gets above 200"- I've heard these stories etc.. But I have always been the guy that has the lt1 where the temp gauge is all over the damn place. is it just my luck? So - I got a 180 (factory TStat) in, its correct & working, I still have been using AC DELCO pumps I believe, have a 3 Core radiator, I just adjusted my air dam because I felt like it was kinda bent from hitting speed bumps and what not so much so i got under my car and made sure no.1 no bags, leaves, etc were blocking my radiator, I made sure all the plastic down there wasn't blocking my radiator- I've never been one to add a "ADDITIVE" as i know - "Radiator repair" and all that **** is just terrible for your cooling system, use factory recommended ( I know there is argument over using regular 50/50 (green) or DEX / ReD , whatever.. Man, I've done my research and I use 4th Gen LT1 F-body Tech Articles <_ SHBoX's tutorials, I have even had a mechanic do alot of my work and go by SHBOX's instructions just to make sure I do everything correct because this **** is perplexing man. Anyways, So randomly my temp jumps up to 235,240 - Its a rather cool night and my car was at 220 225 while driving 55MPH on low rpm...
My next "idea" because i've literally gone over everything - is my tranny fluid is getting hot, and I don't have a tranny temp guage installed and i'm surprised I have waited this long - My solution would be in stall a AUX tranny cooler, I'm fixing to go with a bigger TC so - I'm going to need one as its recommened - Also I live in Arizona (mind you I made it through the summer fine) - Now (our fall) - Ambient temps of 70-92 I'm having Warmer than normal temps... Please someone tell me im not crazy..
I haven't done another flush yet, but I made sure TO bleed my system, my system has not lost ANY fluid, it was a "little" low in the overfill and I made sure to top it off to "COLD FULL" and bled the bleeder just to make sure.. so - Any ideas? Sorry for the rant but this damn car is killing me mentally... This time last year is when I had the final straw with the car and ended up deciding to build the new motor in hopes of turning a new leaf and kissing all my cooling issues good bye..
So update.. Today's drive home from work.. She hit 248-250, then surged down to about 230-235... Faulty Thermo? Thoughts? She has a date with my good ole' SBC mechanic on monday... But I have a very busy weekend - I "may" beable to swap the therm sunday if I get a chance.
Still using OEM fans? Have you verified they are both working on both low and high speeds, and rotating in the correct direction? Is the shroud that surrounds the fans intact? Are you sure there are no open gaps at the sides of the radiator?
Have you read the coolant temps from the PCM, since those temps are what control the fans? Have you verified the accuracy of the coolant temp sensor in the water pump? Or the temp sensor in the head for the gauge? I wouldn’t just dismiss the 160°F t'stat as a gimmick.... they are effective when you also reprogram the fan on/off temps.
When changing the water pump(s) did you check the drive gears for excessive tooth wear?
Check Scan94/95 software. I haven't looked at many data logs including the auto trans, but you may be able to pull the trans temp from the PCM.... not sure though. But the 4L60E has an internal trans fluid temp sensor that connects to the PCM.
A 2-core aluminum radiator is usually better than a 3-core. The 2-core generally uses larger tubes for more coolant flow, and may even result in less resistance to air flow.
Maybe there's more to be learned from that huge, rambling paragraph. I managed to get through it, but I need to run through it a couple times more to be sure I picked up everything.
Still using OEM fans? yes
Have you verified they are both working on both low and high speeds, and rotating in the correct direction? no
Is the shroud that surrounds the fans intact? Yes
Are you sure there are no open gaps at the sides of the radiator? What do you mean?
Have you read the coolant temps from the PCM, since those temps are what control the fans? I will know monday when we plug it into the scanner
Have you verified the accuracy of the coolant temp sensor in the water pump? No. Replace just to remove this as a option?
Or the temp sensor in the head for the gauge? No, Should I replace this too?
I wouldn’t just dismiss the 160°F t'stat as a gimmick.... they are effective when you also reprogram the fan on/off temps. (I know I was just being sarcastic as I see so many people report their low temps that never changhe )
When changing the water pump(s) did you check the drive gears for excessive tooth wear? - No, we are talking about from the ENGINE - Right?
Check Scan94/95 software. I haven't looked at many data logs including the auto trans, but you may be able to pull the trans temp from the PCM.... not sure though. But the 4L60E has an internal trans fluid temp sensor that connects to the PCM. <- Legit about to install a Trans cooler & gauge, only thing that has postponed me is trying to find adequate placement withouit messing with the plastic in the lip
A 2-core aluminum radiator is usually better than a 3-core. The 2-core generally uses larger tubes for more coolant flow, and may even result in less resistance to air flow. Understandable, I got a Excellent price on this one.. and my temps right after install were excellent.
Maybe there's more to be learned from that huge, rambling paragraph. I managed to get through it, but I need to run through it a couple times more to be sure I picked up everything. - My apologies, sometimes I just got to let loose.. This damn car !
I'm going to convey your input with my mechanic (over the shoulder supervisor) and make sure I go over and address it all.. Sensors should be replaced I feel, they are stock! Waterpump gear will be checked.. I'm going to closely inspect the fan and double check the speeds when its on the scanner monday... Also - When my Car was tuner originally my fans were already reprogrammed- I left that part out because I forgot, I called my tuner about the fan reprogram and he told me he already changed them (who could forget this?? me )
The splined shaft that drives the water pump has a gear that is driven by teeth on the back of the cam sprocket. The gear is right behind timing cover. See if there is any play in it, possibly indicating damaged teeth. Also a good idea to make sure the splines on both ends of the coupler are not worn.
An additional thought - since you're in AZ, I suspect your A/C is still operational. Did you check the condenser, in front of the radiator, to see if it’s dirty enough to impede air flow? There are seals on the sides to make sure air can’t bypass the radiator by passing around the sides.
OK guys update.. Sunday Afternoon I had scheduled a time to bring the car by my mechanics and it ran real hot.. headed to 260 world so I shut her down and left her on the road.. Today took the morning off from work to go over the various things with the mechanic.. So i'll report that oddly enough - We bled the system, took it for the first test spin and it was back to 210-220 - It is actually cooling down from 220 back to 205-210 which brings me to the conclusion that air was in fact in my system - and Friday afternoon when I topped off the coolant & purchased a new 180 thermo I actually ****ed up some how when I opened the bleeders. I did it when the car was already hot. He recommended that every few weeks or so I should check my fluids and re-bleed the system.. Obviously now after a few "thermo cycles" I am going to bleed it correctly early in the morning..
I'm curious as to how the system is getting air inside it.. We did a pressure test and it passed..
As for the fan shroud there is a little bit of a gap on the edges of it where it mounts to the radiator (I should prolly find a way to fill in the gap).
We didn't get further- His recomendation was to drive the **** out of it and see what happens & to go from here - (with the understanding after a few heat cycles I bleed it again and top it off)
Your going to pull air into the radiator if the overflow hose, or pipe it connects to on top of the reservoir, has a hole in it. Radiator cools, coolant contracts, resulting vacuum tries to pull replacement coolant out of the reservoir, but leak in the overflow hose pulls in air.
So I took it upon myself and at the advice of my mechanic to drive the hell out of my car to see if I could trigger some issues. Mind you I haven't rebled the system since Monday. Drove 30 minutes one way car got up to 220.... Maybe 225 then cooled back to 220 again.. It goes through its normal cycle in which it climbs gradually in temperature until the 220 mark and doesn't heat up quick I didn't get to 220 until around my destination. Handled my business there then decided to take long way home which is 50 minutes... Started car climbed to 220 in 45 mph traffic and stayed there for about 25 minutes. Then I came down to a intersection where I circle back so to speak.. Turned right after a stop then poof.. Car cools down all the way to 195-200 and stays there. I had another stop ( replace my 7mm) extended socket I use for bleeder valve. Got it got back in car drove the remaining 20 minutes car went back to 220.... Sound like air in the system ? Ive never seen the car cool down so low once it is heat soaked.
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