I am driving a 1974 corvette. It is a 350 engine, but not the original.

I was checking the fluid levels of my corvette over the weekend and found an orange fluid on top of the engine. (see pictures) It has formed a few small puddles on top of the engine. However, it is also leaking down the length of the enginer block, I want to say that it is coolant that is leaking, but I am not sure. I want to get some additional opinons. Also, any recommendations for fixing this problem are welcome.

Thanks.

Lou

 

Looks like coolant to me. Might be coming from your radiator hose or your thermostat housing. Those chrome housings sometimes have an issue not wanting to seal correctly.

You could dry up the puddles and take it for a drive and then check it again while it's hot and see if you can spot where the leak is coming from.

 

Hard to tell what it is unless you get a finger-full of it and rub it between your fingers (checking for lubricity) and take a whiff. If it's oil, it will be slippery and smell like....well, oil. If it's coolant, it will be a little slippery, but smell 'sweet'.

In either instance, the cause is likely that you didn't put RTV black sealant on the last few threads of each intake bolt when you installed them. Castings (intake, head, block) are notorious for having porosity in the metal, caused by air/gas bubbles forming in the part as hot metal is poured in. That porosity can allow small amounts of engine fluids to weep between areas that have been machined following the casting process--like threaded holes and flat surfaces.

Silicone sealant is NOT appropriate for long-term sealing of such fluids with fluctuating temperatures, like engines/transmissions. But, RTV black is formulated specifically for that purpose; it is the only silicone sealant that can do that job well. Another alternative is to use Permatex #2 gasket sealant. I've used both, and both work well.

If you think that might be your problem, you can remove ONE BOLT AT A TIME, clean and dry it well, also clean out the threaded hole; then put sealant on the last 5-6 threads (just wipe it in the threads-don't put gobs on it), and reinstall it. Snug the bolt down, then bring it to the lower end of rated torque. The sealant will act as a lubricant and torquing will put MORE stress into the lubed bolt than it will a dry one.

When you have finished with all the bolts, do a re-torque on them starting with the first one and working through them all. Let the engine set for at least one night before firing it up.

P.S. If you don't have a working PCV system on your engine and that fluid has taken a long time to show up, it could be just collected oil vapors that have condensed on your engine after each use. A working PCV system keeps the engine compartment cleaner, as well as reducing vented hydrocarbon emissions, WITHOUT AFFECTING FUEL MILEAGE OR ENGINE PERFORMANCE.

 

First, take your radiator cap off and look to see what color antifreeze you have, orange or green.

 

That looks like fuel to me, if it was oil I'd think it would be much darker unless he JUST changed his oil, and from what I remember of orange coolant It's a little different shade, could be wrong though

 

Its either orange coolant, or rusty coolant. Looks like its leaking from either the water neck or the hose connected to it. It looks like the upper heater hose is leaking too on the other side. If its rusty coolant, time for a good flush.

 

Ok, now I see the trail of coolant coming from under the hose, I stand corrected yeah I'd agree that it's time for a fluid flush...

 

Either that upper hose is old and swollen or it's the wrong size. I would check that for sure.

 

I'm surprised that no one has mentioned anything about that fuel filter yet. You guys are slipping.

 

It does look a little....inadequate.

 

Just looking at the hose, it looks like the wrong size (diameter) as is the clamp.

 

The connector on the heater supply hose, does it look wet? Does in the picture. I see fluid on both sides of the manifold. Could be a single source and it moves accros the manifold during "spirited" turns.

 

I looked at the engine again last night. The fluid on the engine is coolant. I verified this by checking the coolant I use. It is orange. Also, I was able to soak it up easily with a paper towel. I would not be able to do that if it was oil.

That is about as far as I got. I am going to check the hose tonight and see if there is any cracking and if it is the right size. I will also recheck to see if everything is attached nice and snug.

I probably won't get a chance to drive it again until Wednesday. I will no more then. I will drive it to and from work, and when I get home, see if there is fluid collecting / leaking and from where.

I appreciate all of the advice and help. Keep it coming.

Lou

 

Fuel filter or did you mean air cleaner?

Have heard anecdotal stories of those foam ones catching fire due to a backfire through the carb.

 

Now that i look again, both.

 

The best way to find the source might be to just start it up and let it come up to temp. Then the coolant is pressurized and should be pushing out from wherever it's leaking from.

 

Can't believe you haven't done the simple smell test.

 

Well now where would the challenge be in that

 

Last night I looked at the fluid again. In short, I jiggled the hose. When I did that, I was able to see coolant leaking out, where the connection is between the hose and the thermostat housing.

I think I first course of action is going to be to replace the hose, along with the clamps. While I am doing that, I will check to make sure the thermostat housing is securely fastened.

Thoughts....?

Lou

 

I went ahead and purchased a new hose and clamps. Those are arriving today. I will start fitting them up tonight. ... Standby....