Coolant consumption in 302 efi

It has been some time since I have posted about this issue. My truck with the 302efi is consuming coolant and I am not sure how to go about diagnosing what the real issue is. I suspect it is a blown head gasket, but I want to make sure.

So far, here is what I have noticed.

On cold startup in cold weather white smoke from tail pipe, smells sweet.
On cold start up in warm weather, slight sweet smell from exhaust, no smoke.
In the last month about 1qt of coolant has been consumed.

The radiator cap was in bad shape, the rubber seal was all cracked so I changed it out for a known good one this morning.

Once I topped off the coolant this morning I ran the engine and it sucked and burped some coolant into the system. I am going for a short drive so will try and burp it again when I get home.

What steps should I be taking to correctly diagnose the problem here?

Thanks!

A couple of things come to mind. Sweet smell in the exhaust usauly means bad head gasket or cracked head. That being said, is your oil milkie looking? The other cause is a bad intake gasket. The lower part of the intake has coolant passages that are close to the intake ports, some times the gasket gives away in between those ports and causes coolant leaks into the intake port. The last and least likely is that there is coolant running through the throttle plate area right where the hoses hook up from the air filter, it may have a hare line crack.

Get your hands on a coolant system pressure tester and pump it up to the cap pressure, drain the oil and see if coolant runs out with the system pressurized. If it does, then it could be any or all of the above. If it does not, it could be just a leaking intake gasket

A) Steam, not smoke.
Steam will dissipate, smoke will linger.

B) Water/coolant will settle to the bottom of the oil pan.
You only have to crack the drain bolt to tell.

C) There are reagents to test for combustion byproducts in the coolant.
A couple of drops and you know for sure.

You are correct about the testing for combustion by products in the coolant. For some reason, it dident even cross my mind.

Thank you for correcting me.

Great! Thank you.

The smoke/vapor does dissipate pretty well.

I will check oil at dipstick and drain plug - It was normal last time i looked about a month ago.

Then research the reagents and pressure testers

Steve,
I'm not trying to correct anyone.

Just pointing out there is a test designed to confirm this condition.

Its all good Jim, I use a test similar to that all of the time. I am glad that that you pointed it out. Im not sure why I blanked out on it.

Check where your timing cover meets the block, I had a coolant leak for the longest couldn't find it cause it was slow.  ended up being the timing cover to block gasket I noticed it one day when it got bad enough for coolant to start pooling in the timing cover valley and when hot you could see a small stream coming out.

Its why I got a new timing cover for my 306 build, these covers get pitted over time and start leaking and mine I shouldn't have reused it but I did.

Rusty, is there a passage up there on a 302?
I know how the thermostat location differs on Windsors

I know 'I' have a bypass hose from the front of the intake manifold to the back of the water pump, but the two passages through the timing case are on either side going into the block, to the back of the heads and then forward.

In the back of the timing case should be a convolute groove -between- each water passage and the timing case itself.
Those are there to give indication of a failed gasket -and- to keep coolant from getting into the oil.

I can't tell you how many engines I've found that have everything packed with RTV.
It's not doing any good like that.  

Yep 302`s like 351W engines have coolant passages through the timing cover to the water pump.  There is also a 90* bypass hose from the thermostat housing to the water pump as well.

On my timing cover it is pitted quite bad and the 351W on a 84 we put the motor in the one that we had for over a year and they wont pay or pick it up we had to get a new timing cover as cleaning the timing cover knocked a hole in the coolant passage to the water pump as it was paper thin.

I've fixed some pitting with JB Weld and a large flat file.
Timing cover's only $100, but if you need it -today- you may as well fill it in and put it under a heating pad or halogen light.

Gsmblue wrote

What steps should I be taking to correctly diagnose the problem here?

A leakdown tester would be able to pinpoint which cylinder is bad..... if you find it is indeed a head gasket (or cracked head)
Cracked or holed cylinders also happen, but not often in gasoline engines.

Yep, I got mine from Dorman for $75.  I will just take and run my small pipe tap in the dipstick opening and put a pipe plug in it cause ive seen cup plugs pop out before.

I'm a newbie on the block. Have you found your leak? I'll make a few assumptions here, factory efi, with factory intake, is my assumption.  Also assuming you resealed the motor maybe? Common problem with the factory aluminum intake is that you need to use the graphite style factory gaskets, not used on early bull nose 302. The factory intake is, shall we say thin. It wiggles through the thermal cycle and can cause the paper gaskets to crack near the front coolant passages and leak either externally, into the crankcase,  or into the intake. I worked on these babies when they were new and saw this often. Hope this helps.

I haven’t had a chance to get out to the truck the last couple of days.. I need to check the oil condition and look around the intake and timing cover.

The engine is stock and approx 120k original miles.