Hot Rod Forum : Hotrodders Bulletin Board - Reply to Topic -- Hot Rod Forum

Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans Advertise
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine> new motor overheating - think its the fan/radiator
User Name
lost password?   |   register now

Thread: new motor overheating - think its the fan/radiator Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


Additional Options
Miscellaneous Options

Topic Review (Newest First)
09-02-2018 03:28 PM
MouseFink Vary the speed is the standard break in driving procedure. The slow lane (outside) on the freeway is a good place to vary the speed of the car for about 50 miles.
09-02-2018 02:43 PM
Ford-400-Dan-56# I was planning on driving it on a road where I can vary the speed from 30-65 mph 10 times according to the docs I read online.
09-02-2018 12:48 PM
Originally Posted by Ford-400-Dan-56# View Post
In an event, I was able to run it for 20 minutes at 2000 rpm.
Not acceptable. The whole idea of breaking in the camshaft and lifters is to vary the rpm's so that oil is thrown into different places. Put someone in the driver's seat with a tachometer and have them vary the engine speed slowly up and down from 2000 to 3000 for AT LEAST 20 minutes and I like to run the motor for 30 minutes. Never lost a flat tappet cam this way.
09-02-2018 11:34 AM
MouseFink Breaking in a new camshaft with bone crushing valve spring pressure has always been a problem. Back in the 60s the Super Stockers broke their camshafts in using weak valve springs then changed to bone crushers on race day.

Chevrolet recognized that problem in 1958 and used the same moderate pressure valve springs with the camshafts in both the low and high horsepower engines. The Chevrolet high performance cam profiles were designed to operate properly with reduced valve spring pressure.

My 1962 Chevrolet Bel Air with a 350 engine was equipped with stock “068” valve springs (still available from GM) when the motor was rebuilt in 1969. They set up at 80 lb seat pressure at 1.700”, My engine has the L-79 “151”. Camshaft, which is now now discontinued. Several aftermarket cam grinders offer duplicates of the L-79 camshaft.
09-02-2018 09:08 AM
Originally Posted by MouseFink View Post
A four-core (four-tube) radiator core has less air flow than a three core and must use thermo-controlled fan or electric fans in an attempt to maintain proper air flow. The lack of air flow is the culprit.
I did that and it didn't run any hotter than 175. I also had 2 box fans strapped to the grill.

One problem I had is when I started it up and left the radiator cap off and ran it till the T-stat opened, water came gushing up from where there were hot air pockets in the block.

In an event, I was able to run it for 20 minutes at 2000 rpm.
08-31-2018 09:01 PM
Originally Posted by Ford-400-Dan-56# View Post
10-4 on that.
Use a large floor fan in front of the radiator during the break in run up.
08-31-2018 08:55 PM
ericnova72 16" electric fan combined with 2000 engine rpms, with no vehicle forward movement to augment the air flow through the radiator...that electric don't have a snowball's chance in the hot place of keeping it cool.

It will probably not even get the job done once you are actually able to drive the vehicle, just doesn't pull enough air.

Go back to the mechanical fan and shroud for the cam break-in....and if you have to have an electric after that, go salvage yard trolling and get either the Ford Taurus fan and shroud set-up or the Dodge Intrepid fan and shroud combo.....either of those will probably pull 4 times the air that generic 16" aftermarket electric will.
08-30-2018 08:01 PM
Originally Posted by aj06bolt12r View Post
Not screwing up the cam break in is your biggest priority right now. Idle time and even starting and shutting off the engine repeatedly are risky moves. You don't wanna wipe a lobe
10-4 on that.
08-30-2018 05:07 PM
MouseFink A four-core (four-tube) radiator core has less air flow than a three core and must use thermo-controlled fan or electric fans in an attempt to maintain proper air flow. The lack of air flow is the culprit.

Replace the four-core (inline tube) radiator with a three-core (staggered tube) radiator with a good shroud and toss those “me too” electric fans. Electric fansblock air flow. A good 15” clutch fan will assist a three tube radiator in cooling.

Good clutch fans are expensive and, in the case of GM vehicles, are sometimes difficult to find. I use a Hayden $40 clutch fan. It is cheap but it will not last more than 20,000 miles before it needs to be replaced. A Heyden clutch fan work well with my 1962 Chevrolet Bel Air with a L-79 engine and 4.11 rear gears. My engine cruises at 4000 rpm at no more than 200 degrees and never gets higher than 210 degrees in stop and go traffic on a 100 degree day.
08-30-2018 04:36 PM
Originally Posted by 75gmck25 View Post
What do you mean by a "trailer cam"? -Bruce
Probably a 204/214 durations 'towing' / 'RV' / 'truck performance' cam...
08-30-2018 04:32 PM
BuzzLOL Ford 351M's and 400's use a SPECIAL THERMOSTAT !!! Do you have it? I forget what is special about it, but I know you can't just throw a generic one in!

Make sure the coolant pump isn't sucking the lower radiator hose out flat and blocking coolant flow when the engine is revved... system pressure and/or a S.S. 'spring' inside that hose is supposed to prevent that... Of course, there's no system pressure if the radiator cap is off... so I like to see both things used...

Incorrect, retarded ignition timing and incorrect carb. jetting can also cause overheating...

Did you go from V-belt to serpentine belt system and start turning the water pump backwards?

Also have to make sure the engine/heads were completely filled with coolant... you didn't use a crossflow radiator with a top lower than the engine, did you? If so, will need to use a special coolant fill technique... Also, make sure heater core/hoses are full... turning the heater on full blast also helps cooling the engine... open the vehicle windows... even doors...
08-30-2018 12:37 PM
BogiesAnnex1 The radiator cap should vent to a catch tank so that coolant isn't lost on the ground and after cooling air is not drawn back in.

200 to 210 is not uncommon during the first run in, friction is high with new parts, timing is usually not ideal, along with other tuning issues.

There is always a risk of running a fresh engine against an old radiator if this is your case it may be the old radiator is not up to the heat output of a fresh engine.

First start ups and initial cam break-in should always include a good box fan to insure plenty of air is moving through the radiator core. As has been suggested being prepared to mist some water into the core is a very effective way to knock the coolant temps down.

This first 20 to 30 minutes should be used to get the tune correct while the cam and lifters mate in to each other, this is not a time for shut downs and restarts so you have to be prepared to support problems like cooling so you can continue with the initial run-in and tune ups without interruption.

08-30-2018 11:56 AM
aj06bolt12r Make sure your ignition timing isn't too retarded, that will make it run hot. About 25* advance at 2000 rpm should be fine for the break in. Just have to remember to reset your timing after the cam break in and make sure you don't have too much total timing.

Maybe get the garden hose and mist the front side of the radiator while you are doing the cam break in.

Not screwing up the cam break in is your biggest priority right now. Idle time and even starting and shutting off the engine repeatedly are risky moves. You don't wanna wipe a lobe
08-30-2018 10:57 AM
RWENUTS When I broke in a cam I’d find the biggest fan I could and put it right in front of the rad. That always worked keeping it cool.
08-30-2018 10:15 AM
techinspector1 We seem to have had a rash of overheating threads lately. Perhaps we need to go back to basics. Here is a wiki article that has been polished by several of the members...…
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules
You may post new threads
You may 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

All times are GMT -6. The time now is 06:02 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.