Alloy heads.. overheating?
Thread Starter
Intermediate
Joined: Nov 2009
Posts: 47
Likes: 1
From: townsville q.l.d.
Alloy heads.. overheating?
Hi guys, I've just installed some holley alloy heads on my L48 and (without getting too techy) 490. th lift cam high rise manifold and hooker headers, now it goes quite well but it's running too hot.
Before I toyed with my reliable (but slow) engine it run at 185` all day.
Now it slowly rises to 220 then gets turned off. I know more horsepower makes more heat so I had the radiator cleaned, new water pump thermstat while I had it apart. even tried thermo fans. still hot.
Is this commen? Would a bb radiator cool the little beast?
I'm in Oz and it is hot here so I dont want to import something that wont fix the problem.
Thanks gary
Before I toyed with my reliable (but slow) engine it run at 185` all day.
Now it slowly rises to 220 then gets turned off. I know more horsepower makes more heat so I had the radiator cleaned, new water pump thermstat while I had it apart. even tried thermo fans. still hot.
Is this commen? Would a bb radiator cool the little beast?
I'm in Oz and it is hot here so I dont want to import something that wont fix the problem.
Thanks gary
Advanced
Joined: Apr 2006
Posts: 60
Likes: 0
From: Gold Coast
Have you tested the thermostat on the stove in a pot of water to see if it opens? Did it overheat with both the mechanical fan and the thermo fans? Are you 100% sure there are no air bubbles in the system?
Also, check it with a different temp gauge just to make sure.
Also, check it with a different temp gauge just to make sure.
Thread Starter
Intermediate
Joined: Nov 2009
Posts: 47
Likes: 1
From: townsville q.l.d.
Have I done something wrong in bleeding the system or the stock radiator just wont handle it??
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
What condition is the lower radiator hose? Squeeze it to see if the expansion spring is still in there (or if it is fairly rigid because of its construction). That hose is under suction, and when it gets hot and runs at higher rpm, it can collapse [restricting flow] if it is worn/flimsy.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Under what conditions is it getting hot? How's the temp at speed (like 60mph). When (under what specific conditions) does the temp start to rise? If, when it's hot, you run a garden hose of cold water over the radiator core, does this dramatically and immediately pull the temp down? The system will self-burp so you can neither do something right or wrong there. The stock radiator has sufficient capacity, so you shouldn't be parts shopping at the moment. How is your ignition timing? You running at least six degrees of initial advance and are you using the vacuum advance? Done anything to the carb?
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
First ... how do you know it's truly 220? Did your OE gage read 185 but now OE gage reads 220?
Most alum head retrofits require changing OE temp sending unit and/or its location. When either differs from OE, the output sig to OE gage usually changes too. OE L48 TS location is in head between cyls 1 & 3. What do you have now? A different sender? ... a different location? ... both? ... neither?
I repeat ozzyvet ... check for air ... put nose up-tail down & bleed/refill again.
I doubt clean stock radiator is cause.
Most alum head retrofits require changing OE temp sending unit and/or its location. When either differs from OE, the output sig to OE gage usually changes too. OE L48 TS location is in head between cyls 1 & 3. What do you have now? A different sender? ... a different location? ... both? ... neither?
I repeat ozzyvet ... check for air ... put nose up-tail down & bleed/refill again.
I doubt clean stock radiator is cause.
Thread Starter
Intermediate
Joined: Nov 2009
Posts: 47
Likes: 1
From: townsville q.l.d.
First ... how do you know it's truly 220? Did your OE gage read 185 but now OE gage reads 220?
Most alum head retrofits require changing OE temp sending unit and/or its location. When either differs from OE, the output sig to OE gage usually changes too. OE L48 TS location is in head between cyls 1 & 3. What do you have now? A different sender? ... a different location? ... both? ... neither?
I repeat ozzyvet ... check for air ... put nose up-tail down & bleed/refill again.
I doubt clean stock radiator is cause.
Most alum head retrofits require changing OE temp sending unit and/or its location. When either differs from OE, the output sig to OE gage usually changes too. OE L48 TS location is in head between cyls 1 & 3. What do you have now? A different sender? ... a different location? ... both? ... neither?
I repeat ozzyvet ... check for air ... put nose up-tail down & bleed/refill again.
I doubt clean stock radiator is cause.
I have used all new hoses, I have fitted a new gauge under bonnet to verify the temp(in photo) it's reaching 110 celcius. the original sender unit fitted into OE hole in the head in the same place as before. the manifold is a duel plane weiand stealth and a new 750 V/S holley. The engine cools down with a hose on the radiator.I've tried different timing but if it's not at or close to 12 degrees with no vacuum hooked up, it either wont idle or wont start Tomorrow I'm getting the cooling system checked for exaust gasses. I may have access to a BB radiator soon for a lend, fingers crossed....This is just a teething problem and it will be sorted.
Thanks for your replies guys, Regards Gary
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Drifting
Joined: Apr 2006
Posts: 1,911
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From: gold coast queensland
gerry had very good question....is it hot when sitting in traffic or is it hot on the freeway when cruising or both? if it gets hot in traffic but stays at 180 when cruising you have an issue with not drawing enough air through the rad with the fans .
if its the other way around and fine in traffic but bad on the hiway then check your aid dam to make sure air is being drawn through the radiator.
townsville being so hot your going to need every bit of air to allow a stock 3 core copper/brass radiator to do its job.
even though you have upped the performance alloy heads should keep your engine cooler not hotter.
if its the other way around and fine in traffic but bad on the hiway then check your aid dam to make sure air is being drawn through the radiator.
townsville being so hot your going to need every bit of air to allow a stock 3 core copper/brass radiator to do its job.
even though you have upped the performance alloy heads should keep your engine cooler not hotter.
