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Thoughts on high mileage Mustang Cobras - READ ONLY

54 messages,  Last post on Oct 31, 2002 at 6:18 AM

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Messages Page 4 of 6

#25 of 54 You here to fight or talk about Cobras? by zueslewis

Oct 28, 2002 (5:45 pm)

For that matter, why the subject? To me it's like "would you buy a 140,000 mile Ferrari 355?" It just doesn't matter - I only came in because the word "Cobra" was mentioned.

#26 of 54 We're here to talk about by newcar31

Oct 28, 2002 (6:24 pm)

buying a high mileage Cobra. I thought it was an interesting topic since there aren't too many Cobra DOHC 4.6L engines with many miles on them yet. So far, the speculation of whether or not it is going to last that long is based on other Ford engines. It was relevant to point out that the Cobra 4.6L DOHC engine is not like other Ford engines. Of course reliability depends on how the engine was treated during those miles, but engine design is a major factor. So far, no one has been able to prove or disprove the idea that the Japanese V8s are better with regards to manufacturing tolerances or long term reliabilty. Generally, I know that Japanese designed engines are better than Domestic designed engines, but I think this comparison is unique.

#27 of 54 In my limited, non-credentialed, real world experience by americanflag

Oct 28, 2002 (6:55 pm)

I know I put 209k miles on my 88 Acura Integra. The engine was still running pretty well at 209k, but the a/c went, so rather than replace it I traded the car in on a Honda Civic HX. I traded the Civic in at 90k miles, and the engine was running about perfect. So I have some limited experience putting miles on cars.
 
Back in the eighties, I remember American cars had a horrible reputation for reliability. That kept me away from them until this September, when I got a 03 GT. I am very interested to see how this car holds up when it gets mileage on it.
 
But I notice you guys are drawing a distinction between the SOHC and the DOHC. Wouldn't the SOHC last longer, since it is a simpler design (all other things being equal)?
 
Let's put aside 300k miles for a minute, is 200k miles unreasonable assuming proper maintenance for either of the 4.6 Ford engines? (Also, can we say some nice things about Ford engines because they are, well, Ford engines and not rice burner engines.)

#28 of 54 There are literally gillions by zueslewis

Oct 28, 2002 (7:16 pm)

of 150,000 and 200,000 mile SOHC 4.6s in service. Since the Caprice died in 1996, law enforcement has purchased Crown Vics for 95% of their fleets - a few Impalas, Intrepids and Camaros thrown in. Most retired PD cars become taxis - I saw a 325,000 Crown Vic here in Philly - looked like a reman motor, but two engines in 325K is still great.
 
My only concern about the DOHC 4.6 is that it's high strung. Then again, Saleen supercharges them (not easy on the bottom end) - so does Steeda and Roush. Another choice (other than the '03) is to buy a used up '99-00 (if I can find one) and drop in a crate motor from Probe Industries with a Vortech or Paxton. Could be fun.

#29 of 54 by speedshift

Oct 28, 2002 (11:45 pm)

Shifty, were any of the engines you mentioned built by the factory at the loose side of tolerances so they'd perform better right out of the box?

#30 of 54 by Mr_Shiftright HOST

Oct 29, 2002 (10:36 am)

Well, very high performance engines are generally built loose, yes, for safety and reliability, but your average passenger car engine these days is built to a pretty tight tolerance. In the 60s, I think they were just sloppy, that's all, with no intention one way or the other. That's all the skill they had, most of them.
 
As far as longevity goes, any car that is super or turbo charged is going to loose some engine life. That's just the laws of physics. It might only be 10-15%, and you the driver may never have to "pay the price" if you trade it in after a couple years, but if you stress and engine for more power you are going to lose something in the bargain.
 
As for a Ford dohc going 200K miles, the answer is "it depends". Will all of them get that far---no, I don't think so, because most cars don't get that far---they are crashed, stolen, rusted or some other major component or combination of components fail and cause the car to be retired prior to engine failure.
 
If you scan the average junkyard, you will not see very many 200K+ cars, because there are many factors that send a car to the grave.
 
But certainly will good care and good luck, 200K is no big deal on any modern V8---but it's the exception, not the rule.
 
All I want to stress is this: If you're buying a car with 150K on it, you are buying a car that is pretty much used up. If it has 100K, it's at least 1/2 used up, maybe 2/3. A car is a "total package", not just an engine. After 150K, you're going ot have to start re-making it, piece by piece, as you drive.
 

#31 of 54 by q45man

Oct 29, 2002 (2:02 pm)

The 4.5 liter Q engine is built to a significantly higher tolerance.
 
All specs from the 1992 Q45 shop manual!!!!!!!
Each crankshaft bearing has 6 choices [grades from 0-6] increments of 0.0001". The crankshaft maximum taper is 0.0002".
The main bearing clearance is specified to be 0.0005" to 0.0012" with a recommended 0.0008" and an upper limit of 0.002".
The connecting rod bearing clearance is specified at 0.0013" and a max limit of 0.0026".
There are 5 grades of pistons available in 0.0004" increments and the wrist pin fit is specifyied at zero to a max of 0.0002".
 
I can assure you that an 8-13 MICRON fit is at least twice as tight as a Cobra engine is built too. The Yamaha SHO V8 closest was 20 microns!
Each Q engine has a series of 16 codes stamped into the block showing the grade of bearings and pistons utilized in the build......remember this was Nissan first V8 and they tried to do it right from the forged crank to forged rods to special cast pistons to the expensive bearing girdle [main bearing beam] to attach the 6 bolts per cap.
name any engine designed in 1988 that had 6 bolts per main].
By the way the exhaust values are sodium filled stainless steel, the intakes are just stainless. Viton seals are used thoughout [each cost $8.00 for each of 32 valves].
 
We have at least 7 clients with Q engines over 240,000 miles so 300,000 is easily obtain same with 4 90 LS400 over 250,000 miles.
 
The ones maintained don't smoke, the bad ones do and I have seen 96Q destroyed at 136,000 miles by lack of oil changes.

#32 of 54 OK by newcar31

Oct 29, 2002 (2:20 pm)

There we go! Now we have some numbers. The Cobra's engine wasn't designed in 88' but it also has a 6 bolt main. Who wants to dig up the Cobra's #s now?

#33 of 54 City vs Highway Driving by americanflag

Oct 29, 2002 (5:12 pm)

Another factor would be city versus highway miles. If the guy with a 100k miles on his Cobra put them on in a daily highway commute without starting and stopping alot that is different than if the miles came from city driving. In fact, it occurs to me that if he put 100k on that fast, he probably was doing highway miles. Also, hopefully the owner of the Cobra was 50 years old plus, that would imply conservative driving habits. The best way I can think of to shorten a car engine's life would be to give the car to a teenager or young male driver and let them drive it for a while.
 
Nothing will protect a car against cold starts, and this is going to occur with a car doing alot of city miles, even with a conservative driver.
 
Shifty, what about synthetic oil? If the vehicle owners were using synthetic oil with changes at proper intervals, would this increase the vehicles life significantly? Also, wouldn't this help with cold starts involved in city driving?
 
If I was looking at buying this car, I would want to see maintenance records.

#34 of 54 Thoughts on high mileage Cobras-QUESTIONS TO ASK by jacuzz

Oct 29, 2002 (8:22 pm)

Question one --why do you want to by a Cobra Vs a Z or say a Supra or even a Lexus
 
Question two --if I buy the Cobra how will I use it.
 
Question three-The Test drive should tell you what you need to initially know.
 
other thoughts could be -do I care about re-sale.
 
If the price is right and the engine fails Would I put another engine in the car.
 
Putting the engine aside- is the car fatigued--suspension, interior,leaks -take it out in the rain.
 
Most important is how you feel. To me arguing over a lexus engine Vs a Nissan engine is a mute point. Take a really hard look around on what is really on the road as far as sports cars,,Cobra's
are rare because they are a limited production car, Camaros, supras and Z's are out there, but hey in my opinion there are a heck of lot more mustangs of the same years still around looking and running good.
 
Fun, enjoyment and looks of what you are driving is in the eyes and hands of the beholder. If you like it get it, agonizing over the mileage is important based on how you want to use the car. I know one thing when I see a Cobra,
that looks good I am always impressed.
 
As my wife always puts it you get what you pay for,and if you are buying a high mileage car and that is what it is --a great car with high mileage, heck find out what a engine costs for that Cobra if available, especially if you want to keep it.
 
Fun, function, investment what is it you are looking for, weigh them out, and the answer will be there for you.

Messages Page 4 of 6

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