TTAC Commentator Scorched Earth writes:
Hi Sajeev, my buddy has a manual-transmission, non-turbo 7M-GE MKIII Supra with about 150,000 miles. Supposedly the previous owner had replaced the head gasket at least once. About a month ago it started smelling like burning oil, and the engine is known for being overly prone to blown head gaskets, so he decided to play it safe and take it off the road within 2 hours of the symptom appearing.
Draining the coolant reservoir revealed a sludgy black substance, which we assumed to be oil, within the coolant. Another strike. The spark plugs, too, were swimming in oil. The rest of the coolant, however, was fine. We could not find any coolant mixed in with the oil, either. Furthermore, there was no greyish/whitish substance around the radiator cap.
Still, we went through the arduous process of removing the head. When the moment of truth arrived, the head gasket was found to be undamaged. And at this point, we’re clueless.
The head gasket needs to be replaced regardless since we’ve taken off the head, which will cost about $500. If we can find out what the source of the issue is, that’s fine. But if not, it may make better financial sense to junk the poor car.
Any idea what problem could be posing as a blown head gasket?
Sajeev Answers:
I cut my teeth on this whole Internet Car Writing thing by moderating a nice little corner of cyberspace called LincolnsOnLine.com. I am also waiting for my mail-order Archaeology degree. In the meantime, I suspect my years of dealing with old Lincolns driven by old people, neglected by their second owner and eventually scrapped by their third, puts me in a unique position to understand what/how/why this happened to this Supra.
Check it: the Essex 3.8L V6 in the 1988-1994 Lincoln Continental, also known as the “Essex Machine”. While these motors are well-known head gasket munchers, Wikipedia says the same darn thing about the 7M-GE (http://en.wikipedia.org/wiki/Toyota_M_engine#7M-GE_) in this Supra. Aluminum heads, iron blocks and poor repairs by a previous owner have a common language, no matter what the car.
Here’s what happened, because I’ve seen it with Essex Machines: the previous owner cooked the motor so hard he blew the head gasket and warped the head. (Which, unlike the Essex Machine, isn’t that hard to do with the super long casting of an I-6 cylinder head.) Unfortunately, the previous owner didn’t upgrade the head bolts, upgrade the head gasket or didn’t have a machine shop check the block/head for warping.
Or a combination of any of the above, which is an ugly scenario. With any luck, all you need are a new gasket, head studs, and a machine shop to deck the head. Not a big deal, if you actually spent the effort to pull the head in the first place. So do it, or consider the alternative:
That’s right, either an LS-X or a 2JZ-GTE swap. That’s what I’d do if I had a busted Essex Machine and an LS-4 powertrain in my garage. Yeah, baby!
Send your queries to mehta@ttac.com
Doctor Mehta never botches a diagnosis!
The owner brought the car to a machine shop – the camshafts were scratched and there were metal shards found in the head. The previous owner must have cheaped out in repairing the last head gasket incident.
The head is fully machined and reinstalled; now all that’s left is to bolt everything back on. In 2 weeks or so we’ll see if we have “any luck” or if it’s LS-X time.
I’m here all week, please tip your waitress.
*THUD*… sorry miss…
How would that account for the spark plugs swimming in oil? Unless the valve guides are in extremely poor condition, however the OP made no mention of excessive smoke when running. I suggest you thoroughly check the crankcase ventilation system prior to reassembly. Not sure about the Toyota straight 6 but the BMW mills have O rings that should be replaced with the valve cover gasket to prevent the spark plugs from swimming outside the combustion chamber. JMHO
That’s what I’d do if I had a busted Essex Machine and an LS-4 powertrain in my garage. Yeah, baby!
That’s totally incorrect, silly, disgusting, abominable, heresy…
But you know you HAVE to post pics of it here when it happens :D
“That’s what I’d do if I had a busted Essex Machine and an LS-4 powertrain in my garage. Yeah, baby!”
Sure I’ve always got a couple of spare LS & LT engines of various vintages laying around. (rolls eyes)
So I assume that this warped head warning goes also for anyone who might try to pick up an old Lexus SC300?
I’d say that goes for any modern motor, especially if the block is iron but the head is aluminum. Late model engines can easily crack 200K with basic care, provided you don’t overheat them. For all of us high mileage people, the secret is simple. Change your hoses, belts, t-stat and plastic bodied cooling system parts on a schedule; don’t wait for failure. With the wealth of info on the web, weak spots will be easy to know about.
@golden2husky
Very good advice! BMW E46 is a prime example of a car that should have all of the plastic cooling parts changed every 60-75k. To avoid it is risking disaster.
I think its a bigger deal on I-6s, even the all aluminum ones. They fall pray to warping easier than V-motors. Or it sure seems that way.
I can’t believe how many E46 BMWs I’ve personally seen bite the dust (3) because the radiator overflow tank exploded and the owner didn’t stop in their tracks at the first sign of overheating.