Running warm after top end job
Thread Starter
Advanced
Joined: Aug 2007
Posts: 83
Likes: 0
From: Cambridge Ohio
Running warm after top end job
Thought I would seek advice before taking the motor apart. Before work done motor temps were at 175-180 driving(180 stat). Now motor temps are 190-205 driving at 40 degrees ambient air temp. installed new stat and verified it's opening full before install. Motor work done was all top end gaskets(all fel pro), rolller rockers, port intake and plenum. Timing is set at 8 degrees, advance looks good with timing light. The only thing that makes sense would be low water flow. The water pump pulls the rad level down quick when reving the engine, pump is only one year old, a flow cooler pump from Summit. Radiator looks clean inside and out. I'm hoping I had a brain fart and put one of the intake gaskets on wrong, but both gaskets have the "this side up" facing the intake. Sorry about the long post, just fishing for ideas before I start taking it back apart.
Safety Car
Joined: Jan 2008
Posts: 3,939
Likes: 1
From: Vero Beach Florida
Make sure the stat is opening and that you have fully packed the cooling system. Sometimes it takes a couple try's to get the air out.
I don't think you have any major problems just check to be sure on your coolent level. Fill the system slightly hot and with engine running around 2K RPM's so the pump is pulling water through system.
Last edited by floridamale; May 6, 2011 at 02:47 PM.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
180* stat begins to open at 180*, this should be your Minimum operating temperature, not the maximum temp.
Is the 190-205 city, or highway?
Do you still have the old thermostat? put this back in for a test, if the temps return, then you may have an answer!
Is the 190-205 city, or highway?
Do you still have the old thermostat? put this back in for a test, if the temps return, then you may have an answer!
Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
I know you tested but sounds like you have a 190 in there. Did you ask for a 180 when you bought it or just the stat for the car if you said I need a stat for a 87 vette they are going to hand you a 190.
Burning Brakes
Joined: Jul 2010
Posts: 1,210
Likes: 17
From: When Democracy becomes tyranny, the armed citizens will still get to vote!
From an old thread:
Jack the front of the car as high as you can safely get it. Then run till thermostat opens , with the rad cap off, and rev to 2k rpms. Coolant level will drop. Pour in as much coolant as possible with the revs up and cap it. Let it cool and keep topping off the overflow as needed.
Thread Starter
Advanced
Joined: Aug 2007
Posts: 83
Likes: 0
From: Cambridge Ohio
I had the same temp problem with the old 180 I bought last year from summit. I replaced it with a mr gasket #4364 180 balanced stat. Both the old and new stat cycled the same during the test. The old stat held my temps around 180 all last year. Now the engine is running warm with either stat.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Thread Starter
Advanced
Joined: Aug 2007
Posts: 83
Likes: 0
From: Cambridge Ohio
Radiator is properly packed. I'm still leaning towards flow restriction. If both intake gaskets are showing "this side up" and I have flow through the rad with the stat open the gaskets should be installed right. Has anyone ever seen intake gaskets stamped wrong or should I just pull the intake to be sure.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
I can't imagine you got the intake gaskets on wrong, I would think that you would have trouble reassembling, and a major vacuum leak.
For the hell of it I went to autozones web site and down loaded a picture of intake gaskets for a 1988 L98, not knowing what year you have I took a stab at it. The 88's gaskets are "punched" off center, this makes it very Difficult to improperly install.
Was your ignition timing 8deg before you started the work ?
Could the porting work have caused an increase in temp ?
Do you have any vacuum leaks ?
here's a link to autozone.
http://www.autozone.com/autozone/par...72998_46006_0_
For the hell of it I went to autozones web site and down loaded a picture of intake gaskets for a 1988 L98, not knowing what year you have I took a stab at it. The 88's gaskets are "punched" off center, this makes it very Difficult to improperly install.
Was your ignition timing 8deg before you started the work ?
Could the porting work have caused an increase in temp ?
Do you have any vacuum leaks ?
here's a link to autozone.
http://www.autozone.com/autozone/par...72998_46006_0_
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Could there be blockage in front of the radiator? If there is no heat exchange, it can boil over with 10 degree ambient temps...fans pull air, radiator uses that to trade heat away lowering the temp going back in. A 180 stat would likely give an operating temp of just under that, IF there were good airflow with 40* ambient. Another possibility is the dash/display temp sensor...it can be reading wrong. Check the plug and connection.
A wide temp differential between operating and ambient just makes it cool faster, or slower to heat up.
A wide temp differential between operating and ambient just makes it cool faster, or slower to heat up.
Thread Starter
Advanced
Joined: Aug 2007
Posts: 83
Likes: 0
From: Cambridge Ohio
My bad, 87 coupe. The gasket set is the same one I have. The upper rad hose doesn't build any pressure until the temps get near operating temp. I diaganosed my #7 head gasket issue last year by backing off all16 rocker arms and using a sprark plug adapter to put air pressure in each cylinder and watching the coolant level. I pretty sure I used fel pro 1034 head gaskets as they were recommened by guys here. I'm gonna pressure test each cylinder tomm. before I take anything apart. The heads were machined .006 and I cleaned the blocked and checked the deck and it was flat. I'll post any findings.
Thread Starter
Advanced
Joined: Aug 2007
Posts: 83
Likes: 0
From: Cambridge Ohio
Pressure checked each cylinder with rockers backed off and 100 PSI with a spark plug adapter fitting, no rise on rad coolant level on any cylinder. Gonna try to pull the intake tomm and see what I can find.
Burning Brakes
Joined: Oct 2009
Posts: 773
Likes: 2
From: Minneapolis MN
I wouldn't worry about the problem your having.You might just be chasing your tail.You have increased your performance on your engine,so a slight increase in coolant temps on your stock cooling system may be normal.If it was my car I wouldn't worry.Check to see what temps it idles at & when the cooling fan(s) come on the temp goes back down.Replace your radiator cap if old & anytime you have overheating issues(& don't know when last replaced).I don't think you have ANYTHING wrong if fans come on & engine cools back down.More perf with a untouched stock cooling system would not surpise me if coolant temps were alittle higher than before.Do above test & if it tests ok,leave it alone.That is my Professional opinion
Thread Starter
Advanced
Joined: Aug 2007
Posts: 83
Likes: 0
From: Cambridge Ohio
1700 rpm in OD at 70 mph, 37 degree outside air temp, last year the motor would hover in the mid to high 170's, now it's running around 200. At 90 degree air temp, it seems like a recipie for disaster. As far as performance goes, I believe roller rockers reduce friction which should translate to less heat. As far as performance enhancements goes,I only did the rocker arms, a port match and polish job on the intake, plenum and heads. I did have the heads decked .006 to ensure a flat surface, But I don't see how that could be an issue. Could a exhaust restriction cause this type of problem? I had shop rags stuffed in both sides of the exhaust to keep crap out during the engine cleaning. It would not surprise me in my giddy excitement to get my motor back together that I could brain fart and leave a rag in.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Could a exhaust restriction cause this type of problem? I had shop rags stuffed in both sides of the exhaust to keep crap out during the engine cleaning. It would not surprise me in my giddy excitement to get my motor back together that I could brain fart and leave a rag in.
You can test for this condition, but I don't rember how, I believe there is a Manifold pressure response time test, and some other test's that can be done.
Burning Brakes
Joined: Oct 2009
Posts: 773
Likes: 2
From: Minneapolis MN
1700 rpm in OD at 70 mph, 37 degree outside air temp, last year the motor would hover in the mid to high 170's, now it's running around 200. At 90 degree air temp, it seems like a recipie for disaster. As far as performance goes, I believe roller rockers reduce friction which should translate to less heat. As far as performance enhancements goes,I only did the rocker arms, a port match and polish job on the intake, plenum and heads. I did have the heads decked .006 to ensure a flat surface, But I don't see how that could be an issue. Could a exhaust restriction cause this type of problem? I had shop rags stuffed in both sides of the exhaust to keep crap out during the engine cleaning. It would not surprise me in my giddy excitement to get my motor back together that I could brain fart and leave a rag in.
Your cooling fan(s) don't turn on till 218 degrees so even at 200 degrees its still far from running hot.Make sure you bled the air completely out of the cooling system & replace radiator cap if questionable or old.
Last edited by 94vettelover2; May 9, 2011 at 09:58 PM.
Thread Starter
Advanced
Joined: Aug 2007
Posts: 83
Likes: 0
From: Cambridge Ohio
I have the 200 degree thermo switch installed on it to match the 180 stat, and idling in the garage it controls temp as it should. The higher temp doesn't appear until I'm driving and it warms up rather quickly. I think I'm going to pull the exh manifolds and snake them to the end of the y-pipe to check for obstructions. I have no cats and both mufflers are exhausting so if anything is in there it should be before the end of the y-pipe. After that, I'm putting it back together and will put some miles on it to see what happens.