incredible amount of heat in engine bay.

[Greg Howarth]

ok car isn't over heating but unbelievable amount on heat coming from engine bay.

I had a new 350/325 hp engine installed in my 73 Avanti.

new radiator with 14in. fan and shroud pulling air. today I installed a 12in. fan pushing air .

raised the hood latches about a 1/2 in. drill 3 ,2 inch holes on the inside of wheel wells ( using a drill bit that you would on a door for the door knob).

everything is brand new .oh I also boiled the thermostat.

also installed an air dam.

when I drive the car it will stay at 190 for 10 to 15 minutes. then climb gradually 230. that's when I head home.

Greg's #1 rule with this car is : until all problems are solved . never drive any further from home than you want to walk.

I'm very frustrated with this situation and would like to move on to other issues.

Thank You in advance for any idea's.

[mfg]

This story bothers me and it isn't even my car!!

There's nothing worse than being concerned what the temp gauge is reading while out for a drive....It DEFINITELY causes stress!

One question.....What was the engine temperature/underhood heat situation with the car's ORIGINAL engine.....the same thing or less?

[Avanti83]

Good question on the temperature with the original engine. My 83 355 SBC roller engine runs a steady 200 give or take on the gauge running in 90 deg temps with a 195 thermostat.

First, be sure that the temps are accurate. If so, is the radiator in good shape and the water pump circulating the cooling fluid? If that's ok, I start looking at the engine timing. One thing that can help under hood temps is wrapping the exhaust pipes with insulation but that shouldn't change engine temp. Lastly, be sure you don't have an air pocket in the system.

And yes, It's hot under there. Good luck, Bob

Edited August 31, 2015 by Avanti83

[Greg Howarth]

the old engine would over heat with in 15 minutes but it had lots of issues. that's why I got rid of it.

the new radiator came with a built in transmission cooler ,so we pulled the other one to get more air to the new radiator.

[brad]

Are you using the same hoses? Remember that the suction hose, (lower one) has to have a spring inside to keep it from collapsing. Is it the correct water pump? some are reverse rotation for newer serpentine belt setups.

[PackardV8]

One possibility is ignition timing is retarded.

Pull the distributor and have the vacuum and centrifugal advance verified on a machine.

Confirm the vacuum advance is connected to the correct vacuum port.

The most difficult thing is to confirm your timing tab is the correct one and TDC is actually where it is indicated to be. There are a dozen different front balance damper, front cover and timing tab combinations for SBC. It's possible the timing mark is not actually where it's supposed to be.

jack vines

[Greg Howarth]

Thank You for your input Mr. PackardV8, I'm going to have that looked at this week.

[wildfelr]

Wow Greg...ill have to read this 2 or 3 times..sounds like youve done a
bunch...everything helps a little bit its a cumulative thing......so
lets do a couple other things ...(1) check ign timing with vacuum
advance disconnected and plugged, 7 degrees should be about max. at idle
(1 1/2) check vacuum overall vacuum leaks cause lean mixture and high
temps (major vacuum leaks can be at brake booster and chk unused vac
ports on your carb (there are several) (2) is your fan electric or belt
driven?...if electric is it fully shrouded (most important) and wired to
turn the correct direction? 3000CFM should be about minimum (3) drill 4
or 5 small holes in the thermostat rim to let air bubbles pass (3 1/2)
does it consume water coolant ?? (4)did you completely depolute the
engine ...there are some hidden things that restrict exhaust flow that
should be removed..(if you havent found them ill be glad to guide you)
(5) if you have an automatic trans disconnect the cooler from the
radiator and install an 18" aluminum cylindrical double pass cooler
(mine mounted nicely crosswise behind the air dam..(pic avail) cost
about $40..(5) I installed a high flow Stewart (brand) waterpump...(6) I
would like to see your air dam/spoiler/scoop..is it really doing what
you want it to do...(7) check mufflers for blockage...(hit them with
your fist and see if they rattle)...ya i start getting nervous at 200
degrees..my 305 seldome exceeds 180 now and my fan comes on at
178..thank goodness for cast iron engines...the decline of the auto
industry can be traced back to the beginning of the mass use of the
aluminum engine...just my opinion...BILL RQB3263....my avanti has the
interior and windows stripped out and is in for body customizing and
paint orig Diamond Blue Metalic...Adios for now ...BILL

[wildfelr]

GREG a couple more thoughts...(1) collapsed radiator hose (lower hose is
suction and that would be most likely to get sucked closed)...(2) you
must have a full fan shroud weather electric or belt driven...Ill think
of more later....BILL RQB3263

[wildfelr]

RQB3263....Itsa pain but you may have to pull the waterpump and compare the inpeller w the old one ...There correct if it was setup for a serpentine sys it wont cool and i dont know any other way to check it ....Ive seen this happen before...thank goodness for cast iron...RQB3263

[PackardV8]

i start getting nervous at 200 degrees

Just to keep things in perspective, beginning in the late '80s -'90s, Corvette cooling fans didn't even come on until the coolant temp hit 230 degrees.

jack vines

[Greg Howarth]

Once again thank you everyone for your input. I have 5 days off from work coming up. So maybe buy next week i'll have this problem solved.

wildfelr thanks for your input, that's a heck of a laundry list , but I can check most of it off quickly.

Once again thank you to everyone. you guys are great.

if you haven't caught on yet , I'm a rank amateur at this .

[IndyJimW]

Not sure you have a problem.

I'm a professional mechanic with 40 years experience and something doen't sound right in your explanation.

There is no air flow problem that I can find with the Avanti design, so there is no reason to be pushing and venting all this air.

Is the engine overheating? Coolant overflowing?

What thermostat are you running?

You say that the new engine runs hot like the old engine.

Did you use the same coolant sending unit and temperature gauge in both engines?

Could they be reading wrong?

What are the actual engine temperatures? Use a handheld temperature reader to check.

I'm running a GM TPI system in my Avanti and the computer operates the fan just as GM designed it to, on at 222* and shuts off at 200*.

Most of the time my engine operates at 205* and rarily does my fan come on.

[lschuc]

Also, make sure that there is no air bubble or air pocket in the cooling system. If your engine block, heads and radiator were completely empty, you may have thought the cooling system was filled with coolant, but there could still be an air bubble or air pocket that has not worked out of the system. That would also cause your temperature gauge to run hotter if the coolant was not circulating very well.

[Greg Howarth]

Hi everyone,

I did a little adjusting to the timing and turned the ideal down a hair. Also had a new exhaust pipes and mufflers done . The car is much better, I was out most of the day yesterday and car ran fine no overheating. Just want to say thank you to everyone for your advise. Stay tuned because this car was a basket case when I bought it and I am slowly fixing it up.

[plwindish]

Greg,

How are things going with the Avanti cooling? Has it settled back down? About the only thing not covered above is shocking your gauge to see if its recording the temperature properly. Hope you have found a solution by now as the whole overheating thing is a real bugaboo to deal with.

[Greg Howarth]

Now that the weather has finally cooled down in Plano, Tx. the car doesn't over heat. Went for a 20 mile drive today and the temp stayed at about 190. happy happy..

Now I can move on to other projects. carpets are next, cabin and trunk. I'm trying to locate a remnant , black 6x12 and make my own.

oops almost forgot ,my son and I put a second layer of dyno mat under the dash and on the floor . helps a lot with the heat coming through.

Edited October 11, 2015 by Greg Howarth