Lightning's cooling problems

OK, I have been having some problems keeping the 351W cool. I have already changed the waterpump(about 9,000 miles ago), the thermostat(180), and put a brand new radiator in. It usually gets hot when I am on the interstate at cruising speeds, or about 65-75. It gets all the way to the L in normal or past it, as soon as I slow up it usually cools down to the R-M range. Then when i get on a regular street it goes all the way down to the N-O range. I need to figure out the problem and get this thing fixed. I think its either going to be an intake gasket or head gasket because coolant spews out of the overflow tank sometimes. How do I know for SURE whether it is a head gasket? I want to get this thing fixed once and for all, I don't care if I need to pull the heads off(in fact it is an excuse for more mods) but I don't want to if I don't have to. Any other idea's on what could be my problem???? Thanks in advance! Erik D. '94 white lightning

Reply to
Erik D.
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Heh,

I saw that happen on a Lebaron once, my friend had the electric fan connected backwards so when you speed up, the wind kept the fan from cooling... I kind of doubt that is your problem (you probably have a clutch fan) but I just figured I would toss that idea in...

CoogarXR

1983 351w Project
Reply to
CoogarXR

If you suspect a head gasket, take the truck to a shop that does smog checks. They can use the tail pipe sniffer to see if you have HC in your radiator. If you get a signal you know the gasket is toast.

Erich

Reply to
Kathy and Erich Coiner

When you changed the water pump, did you install a high flow pump? It's possible at cruising speeds, the coolant is flowing too fast through the radiator, not giving it a chance to cool, before it heads back to the motor. Does it have the fan/clutch setup, or an electric fan? If it has a fan/clutch setup, its possible that the clutch is starting to show signs it's about to go south. At cruising speeds, it's possible the fan clutch is freewheeling. Also, what mods have been done to it? There's a possibility that it is just running real lean at the upper rpms. What I'd do is take it out for a cruise and get it to where it shows it is getting hot, and quickly pull over, and shut the motor off without letting it idle too long, and pull a plug and see what it looks like. You can let it sit and cool down a little if you don't like working on a hot motor. Either that, or put it on a dyno and see what it's doing at the upper end of the rpm range. Just a few thoughts.

Reply to
GEB

This is just a guess...

Maybe the radiator hose is collapsing at highway speed??

Pop the hood and rev the engine to about 3000-4000 rpm and observe the lower radiator hose.

Reply to
func760

a company named johnson makes a kit to test for exhaust gases in the radiator. it's simple to use and costs about $25-$40 depending on who you buy it from. its pretty reliable

//Jeff

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Reply to
orangespawn50

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