Engine overheating. Any advice?

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dutchlincoln79
Posts: 103
Joined: Wed Oct 24, 2007 1:20 pm

Engine overheating. Any advice?

Post by dutchlincoln79 »

Hello,

I'm in a bit of trouble now.
My engine is overheating, and i leave for vacation with this car within 5 days from now :(

The engine sometimes reaches its criticat temperature of 215 degrees.
There are some things that i've done by now in order to reduce heat, so read along, and chime in where you can give advice please...

My rearend bearing was broke, so i replaced the complete 9 inch rearaxle. I have powdercoated the new axle, and put a trac-loc (limited slip differential) in it with gearing 3.25:1, instead of the stock 2.75:1.
My thought was: 20 percent more RPM, s, higher running waterpump, so more coolant flow, less drag on the engine, making less heat.
By the way, the engine is equipped with an impco 425, no carb. anymore.
I had an Innovate wideband lambda, but it's broke...
I also have an aluminum radiator with 2 electric fan's, and a 180 degree thermostat.
Now, my local shop says he's not that happy with aluminum radiators, as copper still cools better (he says).
So, today i swapped the aluminum for the old (1.5 years old) copper radiator, and made a testdrive with my new 9-inch and copper radiator.
Temp. went up to 240 degrees!
I slowly went home, temp stayed above 215 degrees.

Now, the ignition i've set a little too advanced, as when hot, the engine won't start.
So, i backed the advance, let it cool down a bit for an hour, and tried the same trip.

Now the engine got to 215-220 degrees, so ignition helped, but still too hot.

last few days i renewed spark plugs (1mm gap), changed oil and filter, and put a new air filter in.

i hate to say, but currently i'm out of options...
The only 2 things i can think of, is ditch the electric fans (which were great last year to sahara-hot Italy) and put the stock shroud and fan back, plus adjusting the 425 for max. power ( i believe afr 13) wich have it run a tad cooler.

I'm a bit panicking now, as the vacation comes closer and closer, and i can't leave with this car getting soo hot.


Anyone got a good advice?

by the way: i't a '79 lincoln towncar with a 400 engine.

Thanks!!
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storm
Posts: 796
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: Engine overheating. Any advice?

Post by storm »

dutchlincoln79 wrote:My thought was: 20 percent more RPM, s, higher running waterpump, so more coolant flow, less drag on the engine, making less heat.
More coolant flow doesn't always work like this, you need to give the coolant time to cool down in the radiator. Making more water go through faster than it went before can actually give it less cooling time.
dutchlincoln79 wrote:I also have an aluminum radiator with 2 electric fan's, and a 180 degree thermostat.
Now, my local shop says he's not that happy with aluminum radiators, as copper still cools better (he says).
So, today i swapped the aluminum for the old (1.5 years old) copper radiator, and made a testdrive with my new 9-inch and copper radiator.
There are many conflicting theories, I personally prefer alumimum radiators but that's just me.

Do you know the condition of the old radiator? Have you had it checked and cleaned considering it has been out of the car for 18 months I would think that would be a thing to do. You don't say if you put a new thermostat in either, it may be a simple issue with the thermostat. Have you flushed the cooling system, both ways, until the water coming out is clean and clear?

Do the basics first. Things that actually have a primary effect on the water temp, thermostat, coolant, radiator, hoses (check they are not collapsing restricting coolant flow to much), fan belt, electric fans (have you verified they are coming on), airflow into and out of the radiator (are the fins in the radiator, and the air conditioner if you have one, clear).

Now you have that all verified move onto other items. Engine oil level and oil quality, transmission fluid level and quality (you may find the trans fluid has got to hot now and may need replacing as well). Are you brakes free and not causing any drag issues? Is the new rear end ok? I cant tell from your post if this started immediately after the rear end went in, if it did start checking it is ok because if it is dragging it can cause issues.

For the time being I'd set the initial timing to standard (petrol) settings. Once you have the engine running cool again you can change it back.

Hope this helps.
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Engine air flow requirement calculation: CFM = Cubic Inches x RPM x Volumetric Efficiency (VE) ÷ 3456

Steptoe
Posts: 1504
Joined: Fri Feb 02, 2007 8:32 pm
Location: JAFA , New Zealand

Re: Engine overheating. Any advice?

Post by Steptoe »

My experiance is mainly in 1st/2nd gen camaro and GM around that period.

Much repeated above post...the rear end speeding up the water pump sry..thats crazy.

Bradd/cooper radiators of that period where way over built, and the clutch fans by far the most reliable and efficirnt colling systems even on modded street cars.
The problem that arises in taking this over building for granted...failing good maintaince and eventual blocking of some cores that requires manual cleaning by removing headers...often can be checked by 1st fire up of the day, as the thermstat opens feel for cold areas on the radiator...blocked or restricted cores

Another common issue is the bottom hose...it has a reenforcing spring inside, over a long period it corrodes away, and the hose becomes soft....so when you are ctuising down the highway, it sucks closed, slow down and it upens up again.

Also common is the thermstat...faulty, and when replacing NEVER assume it is working correct....put in a jug with a thermometer, heat/boil the jug and see if it opens at correct temp and fully opens.
Another issue, not as common is the thermosta has the wrong /too small an opening.

Having the shroud and fan located in the correct postion in the shroud is critical.
Now, the ignition i've set a little too advanced, as when hot, the engine won't start.
I dont get this..the more advanced the harder to start... too much advance uptop and an engine will run hot.
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C3H8
Posts: 1129
Joined: Fri Sep 09, 2005 11:23 pm
Location: Winnipeg, Canada

Re: Engine overheating. Any advice?

Post by C3H8 »

All good advice. Keep in mind that the fans on a vehicle are mainly important in city traffic. Steady state on the highway the airflow going through the rad should be plenty to keep an engine cool without any fan activity except in the hottest weather. I would lean more towards a water pump problem or restricted coolant flow issue.

Other things could include a leaky head gasket causing air locks in the system altough this will usually cause venting of the coolant through the overflow.

DODGEN1
Posts: 53
Joined: Fri Nov 07, 2008 12:30 am
Location: NORTH CA

Re: Engine overheating. Any advice?

Post by DODGEN1 »

dumb thought. is it really getting that hot.? lasy year my manual temp gauge wigged out. temps went to 240 and above. used a ir thermo never coud find it that hot. changed the gauge running in normal range after that. has it boiled over with the temps youve got?

Steptoe
Posts: 1504
Joined: Fri Feb 02, 2007 8:32 pm
Location: JAFA , New Zealand

Re: Engine overheating. Any advice?

Post by Steptoe »

Yep head gasket...and that will not always cause overflow or buble in the radiator, it it is small and just causes hot running
Head down to the local workshop and ask them to run a HC check...this takes 5 mins and the fluid is re usable..most shops here do it for free
Or the radiator cap is wrong pressure or stuffed.
My Spelling is Not Incorrect...It's 'Creative'

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