Luckily, this is about my 100% stock '97 F150 and not my Mustang... here are the symptoms and I am looking to narrow down the cause (and my possible expenditure)

*truck idles and runs fine, down a little on power under load but has 120K
*started pinging under load this summer unless I ran 93 or better octane
*after a long highway drive my oil is frothy when I open the fill cap
*regular drives to store = no oil froth
*Anti-freeze was oily when I flushed on Nov (I do this anually)
*Temp gauge sits right where it always has
*replaced thermostat with OEM replacement when flushed coolant
*When it is below 30 degrees, I get little to no heat from the heater for 1/2 hour... above 30 degrees and heat works as if normal
* No visual leaks other than rear main oil drip..usually have to put a quart in every other month
* No water in oil
* Plugs look normal but I have not pulled them after a spirited highway drive

All signs indicate head gasket but there are some intriguing reasons to think maybe not as major. What would a blown coolant hose under the intake do?

 

You neednt say what motor you have but I would try this first. Replace PCV valve (cheap) The ping would be coming from a bunch of different things such as:
1 Do you hear any noise from the front of the motor, like chain slap
2 The system may being leaning itself out ie; O2 sensors, MAF, restricted exhaust.

May be able to provide more once I know what motor.
Hope it turns out to be as something cheap like changing the air in the tires.

 

antifreeze was oily? like there was motor oil in it?

 

Sorry, you're right. It is the 4.6L. No noises overall other than slight tapping at start-up for the first 30-60 seconds then goes away and idles/drives fine.

PCV would be a welcome repair. I can try that this weekend. I did the O2 sensors over the summer but didn't clean the MAF. I only run the paper filters in it so never even crossed my mind. I did (at one point over the summer, have a leak in the intake tract between a rubber and plastic piece that didn't go back like they were supposed to (before the throttle body). Drove it like that for a week before I figured out what I had done. fixed the leak and unhooked battery to clear code/reset.

Yes, it appears there is some oil in the anti-freeze. Doesn't look like the Exxon Valdez but enough to turn the pretty green into a greenish brown. No water in the oil though.

 

You seem to need a general rebuild/freshening. I'd include a valve job and new rings and bearings.

The oil frothing I'm betting is due to excessive ring clearance and subsequent quick pollution of the oil with particulate and acidic greases and fuel/combustion by-products. The bearings have had a nice long life pulling a heavy *** truck and are no doubt a little worn by now which is effectively lowering your oil pressure and allowing the lifter tap you seem to be hearing.

The head gasket may be weeping by now and the valves and pistons are most certainly coated with crap or the 93 octane wouldn't be needed (the carbon buildup leads to pinging as it starts to glow red when the engine is really singing).

The thermostatic/cooling issues I would imagine are related to the weeping head gasket. There's just enough oil making its way into the cooling system to sludge it up and you just need to strip that bastard down and tank it and put it back together.

Those are assumptions based on my understanding of your problems. I could be wrong but I think I'm right. smear some of the frothy oil on a piece of white paper as well as a smear of your coolant with the oily goop and I'll be able to tell better what's going on.

 

I can do some smearing this weekend, thanks for the guidance....


So..... maybe I yank the 4.6 from the Mustang (only 40K miles) and drop into the truck, then do a 5.4 swap into the Mustang.....hm,mmmmm

 

That would be fantastic for both vehicles. And not too expensive with all those donor motors laying around.