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I've got some "dirty mayonnaise" in my oil cap, so clearly I've got coolant leaking into the oil and the head needs to come off. But just wondering if there's any way to determine if the cause is a cracked head or blown head gasket before getting the head off. I'm sorta inclined to replace the head regardless, but if it truly is just a gasket issue I may not bother.
FWIW, I did a compression test today and clearly all is well there. Compression was tightly bunched from a low of 150 to a high of 157.
The 'dirty mayonnaise' under the oil cap can also be caused from a lot of cold, short trips. I've been having that issue for the last few months since I've only been driving to work and back (8 mile round trip). Barely enough time to warm up by the time I park and shut it back off.
Been kind of a pain because I can't check my oil level.
Finally took it for a good 40 mile interstate drive Saturday and my oil cleaned back up and the yellow foam went away.
Your compression looks great. Don't jump to the conclusion that you have an issue quite yet.
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1981 Ford Bronco. 300I6 Offenhauser DP Intake Holley 600 4bbl, 31" BFG A/T, NP435, 3.00 rear 9" EFI Manifolds. 2.5" high flow cat/muffler.
1984 Ford Bronco. 300I6 Offenhauser C Intake Holley 600 4bbl, 31" BFG A/T, NP435, 3.55 rear 8.8" EFI Manifolds. 2.5" high flow cat/muffler. Supermotors Pics
What AB said. This condition is not necessarily an indication of a blown gasket or cracked head. It is normal for cold starts and short trips and the symptoms you describe usually start showing up on this Forum in the fall and early winter. But you can have a pressure check done on the cooling system to put your mind at ease.
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1983 F150 300 I6, Comp Cam 260h and lifter kit, Port/Polished head, Offy DP Manifold, Holley 4160/1848-1 465 cfm, EFI Exhaust manifolds, Walker Y Pipe to 3-Way Cat, generic Turbo Muffler, Recurved DSII, Mallory HyFire 6a & ACCEL Super Stock Coil, Taylor Spiro Pro Wires, EFI plugs.
The data-point I left out was that after shut-down the coolant gurgles and blows out the tank somewhat violently.
The truck is new to me, and so far I've only taken trips in the 25-50 mile range, so not a condition caused by short trips.
I'm rather confident that I have a blown gasket. The only question for me is whether I should replace the head rather than just toss a new gasket in there.
The data-point I left out was that after shut-down the coolant gurgles and blows out the tank somewhat violently.
The truck is new to me, and so far I've only taken trips in the 25-50 mile range, so not a condition caused by short trips.
I'm rather confident that I have a blown gasket. The only question for me is whether I should replace the head rather than just toss a new gasket in there.
As mentioned the mayonnaise is probably just cold weather stuff, won't happen nearly as much with synthetic oil. When you have coolant in the oil, the oil is a brown or white milky color down in the pan and usually caused by a cracked block from frozen winter temps. If the oil from the pan on the dipstick is normal, then your oil is ok.
Usually a blown head gasket or head crack either sucks coolant into the combustion chamber (exhaust tastes sweet) or more often blows combustion gases into the cooling system (usually at cold startup) causing it to over pressurize and you will see bubbles with the cap off.
Most parts stores will loan you a pressure tester for free for the cooling system.
The boiling over at shutdown is usually just an indication of a dirty system in very poor shape.
Use a coolant pressure tester first, if it leaks off, pull the head, check the head gasket for tales and have the head magnifluxed. If there is a lot of mileage and the valves and guides are worn out, then I would just get a new or rebuilt head, cheaper, but your call.
I would use a severe duty head gasket and have switched to ARP studs instead of the YTQ bolts that have failed on me before, Probably just poor quality bolts these days.
You need to do further diagnostics before pulling the head. If you do pull the head carry it to a shop and have it checked, it'll need to be surfaced anyway.
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Appreciate the input. I'm new to this engine - most of my experience is with OHC engines. Okay, so next step will be a coolant pressure test.
I should add, one of the other things that leads me to believe the head is cracked and/or gasket blown is the evidence of copper particles in the coolant jug from one of those magic elixirs that "fixes" cracked heads and blown gaskets.
Just coming inside after doing the pressure test. Pumped it up to 15 lbs and it very slowly (~10 minutes) bleeds down to 10 lbs. There's a little bit of leakage that I can see and hear from one of the radiator end tank gaskets - not enough to even drip - just some weepage. Other than that, I can't see or hear any leaks. I pumped it up three times with the same results.
There's definitely a bunch of that copper goop in the coolant system. I'm not sure if it was put in to fix the leak in the radiator, head gasket, or head. Perhaps it worked but now the coolant system is marginalized?
Other than the boil-over after shut down I'm not experiencing any obvious signs of overheating. The gauge has never moved beyond half-way.
From all your symptoms, it sounds more like your radiator is leaking and probably crudded up, making you look elsewhere.
It has to be replaced anyway, so I would start there, they are priced pretty reasonably these days.
I would do an extensive flush first with the old rad in there using some prestone superflush or oxalic acid (wood bleach rinsed with washing soda). This was the old Prestone product the epa knocked out. It's a pita do do it right, but it's only a one time deal if you change coolant every couple years.
Then install the new rad with new cap and tstat and go from there.
You may find that nothing else is wrong.
I would do an extensive flush first with the old rad in there using some prestone superflush or oxalic acid (wood bleach rinsed with washing soda).
This ^^^ is exactly what I was thinking of doing as a next step, so thanks for confirming that I was on the right thought process. The 4.9 w/ MT radiator is ridiculously cheap - found a new one for $68 shipped on eBay - someone tell me quick if there's a reason this is a bad choice... eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices
I actually have some oxalic acid (powder form) so I'll probably use that to flush the crap out of this thing first as you suggest. I'd never heard of using that before, so thanks for the heads-up on that.
Lastly, just to confirm, if I actually had a cracked head and/or blown head gasket it most likely would have revealed itself with the pressure test, yes?
Lastly, just to confirm, if I actually had a cracked head and/or blown head gasket it most likely would have revealed itself with the pressure test, yes?
I would be doing something called a leak-down test (and not relying on pressurized liquid to make itself known to me).
Basically, pressurize each cylinder one at a time and then watch/listen for leaks.
No need to get fancy with two gauges and measure percentage lost, just take the hose from a compression tester (that doesn't have a check valve in it) hook it to an air compressor, bring the cylinder to TDC, screw it into the target plug hole and put about 50 lbs of air pressure in it.
Air in the carburetor = leaking intake valve.
Air in the exhaust = leaking exhaust valve.
Air in the crankcase is getting past the rings.
Bubbles in the radiator would be....... a bad thing.
This ^^^ is exactly what I was thinking of doing as a next step, so thanks for confirming that I was on the right thought process. The 4.9 w/ MT radiator is ridiculously cheap - found a new one for $68 shipped on eBay - someone tell me quick if there's a reason this is a bad choice... eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices
I actually have some oxalic acid (powder form) so I'll probably use that to flush the crap out of this thing first as you suggest. I'd never heard of using that before, so thanks for the heads-up on that.
Lastly, just to confirm, if I actually had a cracked head and/or blown head gasket it most likely would have revealed itself with the pressure test, yes?
When you flush: Be sure to do the flush with the old rad still installed.
With cold engine run water thru it until all antifreeze is gone.
Use the oxalic (9 dry ounces) mixed with regular water and drive it with it in it for at least 4 hours.
Rinse really well and use washing soda (2 dry ounces) mixed with regular water, not baking soda to neutralize.
Rinse really well and refill with water.
Install new rad.
Do pressure test again for head/gasket leaks.
If it then tests good, empty water and fill with 50/50 mix of coolant and distilled water. Change it once a year preferably (only 15 bucks) and you'll never have to do the serious flush again.
Make sure there are no air pockets.
Check that tstat has a bleed hole in it to let air escape when filling, or drill a small 1/16" hole in tstat.
Never put cold water in a hot engine.
It's a real pita to do it right, but worth it. I probably go thru 100 gal of water when I do it.
Nothing wrong with the ebay rad, got an new alum one for wife's caravan for 80 bucks locally.
Cracks usually show up with a cold engine. Head gaskets can be tricky, they might not always leak but will use water over time thru the heat cycles.
Make sure you get a rad cap with a spring loaded poppet (Stant 10230), not a gravity or drop vent style.
I would be doing something called a leak-down test
I already own a leak-down tester, but generally that's used as a diagnostic tool after a compression test indicates an issue. As noted above, I've got excellent compression numbers, so I don't think I'd find anything telling from doing a leak-down.
When you flush: Be sure to do the flush with the old rad still installed.
With cold engine run water thru it until all antifreeze is gone.
Use the oxalic (9 dry ounces) mixed with regular water and drive it with it in it for at least 4 hours.
Rinse really well and use washing soda (2 dry ounces) mixed with regular water, not baking soda to neutralize.
Thanks for the very thorough details. I definitely won't install the new rad until I'm convinced that I've gotten all the gunk out. If that reveals a blown head gasket or cracked head, so be it.
Relative to the "washing soda", is that the same thing as this? 20 Mule Team™ Borax
I happen to have a box of that. It was recommended as an ant repellant - in fact, I need to do my annual application of some around the perimeter of the house - thanks for the inadvertent reminder!
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