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Head Gasket or deeper?

5K views 13 replies 8 participants last post by  speede5 
#1 ·
So I'm looking at a Mazda with a 2.0 4 banger. The guy says its got a bad head gasket, so he's firesaleing the car. It's an 03 with 135K (Km) on it, in really good shape.

Oil is milky, he says it wasn't overheated, just started stumbling and stalled and was parked. It turns over fine, no bad noises, but it didn't catch. I didn't really want it to fire, just hear it spin.

So what are the chances this is simply a head gasket? What are the chances it's deeper, cracked head/block? I can get a whole motor, used (95K) but with waranty and if I were to do that, with the price on the car I'm ahead a bit. If it's just a gasket I'm really ahead but If I do all the work to this motor and then have to replace anyway I'll barely break even.

I would of course strip this one down and see what it looks like, check the head for cracks etc. Not at all scared of the labour, I just don't have the diagnostic experience.
 
#5 ·
speede5 said:
So I'm looking at a Mazda with a 2.0 4 banger. The guy says its got a bad head gasket, so he's firesaleing the car. It's an 03 with 135K (Km) on it, in really good shape.

Oil is milky, he says it wasn't overheated, just started stumbling and stalled and was parked. It turns over fine, no bad noises, but it didn't catch. I didn't really want it to fire, just hear it spin.

So what are the chances this is simply a head gasket? What are the chances it's deeper, cracked head/block? I can get a whole motor, used (95K) but with waranty and if I were to do that, with the price on the car I'm ahead a bit. If it's just a gasket I'm really ahead but If I do all the work to this motor and then have to replace anyway I'll barely break even.

I would of course strip this one down and see what it looks like, check the head for cracks etc. Not at all scared of the labour, I just don't have the diagnostic experience.
Head gaskets usually don't just fail, there are underlying causes. The most typical is overheating, I know he said it didn't, but I'd put a bridge he owns in Brooklyn against that statement any day. Another good cause is freezing the coolant which either cracks castings or by plugging the radiator causes overheating. Another option is its been raced, this increases operating temps and pressures and if held long enough will blow out factory gaskets which usually aren't strong enough to hold these forces when they are presented frequently and or for extended time periods. Another possibility with modern coolants is the stuff got contaminated and went acid then started eating gaskets. In most of these there are probably warped and possibly etched/cracked castings that are causing the gasket failure.

As you can see there are a lot of ways to loose and few to win, I'd walk away from this deal. It ain't often you get to look in the horses mouth before you buy it, but in this case you already know the teeth and gums are shot, it probably won't get any better after you buy it.

Bogie
 
#6 ·
The only way to tell for sure is to pull it apart. Most likely you need a head gasket and to have the head resurfaced. The gaskets will fail if the antifreeze is never changed and the additives that are supposed to control corrosion and other bad things wear out. Head gasket failure is not uncommon and if you do it yourself is not that expensive.
If you do decide to do it spend the money and send the head out to be surfaced and checked or you may be doing it again. I would also use new head bolts when you put it back together. They get weak over time and may not torque properly.
 
#7 ·
Manufacturer recommends new bolts for the head. Already talked to the machine shop and they will check/surface the head for me.

Pretty sure it hasn't been raced. The car is in good shape, all stock, no mods. I need a project and a decent commuter car right now so I'll give it another look tonite.

And yes, I take everything the seller says with a grain of salt. At least he didn't tell me it was his grandma's car!
 
#9 ·
The cylinders were already full of fluid and the oil was contaminated so it was pretty obvious there was a leak. Would a pressure check have shown me much more? I cracked it apart before I read your post, but in the future I'll try and remember that.

Here's what it looked like, the head and deck look ok for cracks. Head is at the machine shop for surfacing, crack and vacuum checks. should have it back on friday.

Pretty happy so far, the head gasket didn't have any holes but it had fluid all through the front so it was most likely the culprit.



 
#10 ·
Take a good look at the head gasket. I hope you took it off easy like.You should be able to spot the problem if it is just ahead gasket.
Material disintegrating next to coolant passages and oil return passages is a good indicator.
Maybe post a bunch of pics of the gasket. That could be fun for everyone. :thumbup:
 
#11 ·
latech said:
Take a good look at the head gasket. I hope you took it off easy like.You should be able to spot the problem if it is just ahead gasket.
Material disintegrating next to coolant passages and oil return passages is a good indicator.
Maybe post a bunch of pics of the gasket. That could be fun for everyone. :thumbup:
that is correct.my 28 yrs. of being a mb tech we had problem like this milk shake in coolant res. everyone had head gaskest failer at the oil passage ..contact your dealer to see if this was a common problem.
make sure to flush out the whole coolant system good afterwards .or rad and heater core could be somewhat plugged up.
thats some nasty stuff and thick,
 
#12 ·
The head gasket didn't appear to have any holes blown through it. The front (exhaust side) was separated and wet throughout, the back side was intact and still laminated. I took it off very carefully so the traces of fluid throughout the gasket were there before I took the head off. These pics are all I have, gasket is with the head at the machine shop. There was no oil in the coolant, but lots of coolant in the oil. I was thinking once it's back together just running straight water and a flush through and runnning it for a bit, than drain and fill proper. Sound good? Same with the oil, run it for a bit with a engine flush added to the oil, then drain and fill.

I was thinking, after its' all back together I could probably pressure test it with the oil pan off to see if anything is creeping through the block.



 
#14 ·
So I finished this one up last month, problem was a bit deeper than I hoped but not terminal.

Head gasket didn't look terrible when I took it apart, found out the head was warped .010". Got lucky and found a head at a wrecker that was in great shape, no machining necessary so that didn't really affect the total cost. Pretty sure oldbogie was right about the overheating, I should have noticed but the rad cap wouldnt seat, due to the rad cap flange being all chewed up. I'm guessing the previous owner lost coolant and overheated things.

I guess I got lucky a bit, and learnt a bit for the next 'deal' that comes along. The car runs awesome, everything works and it gets great mileage, oil is clean as new after 1000km, coolant is clear as well. I could probably make a grand if I sold it today, so I'm not in the hole. Easily could have been though, my contigency fund was to cover things I couldn't find due to no test drive, (clutch, suspension) and it got eaten by the rad, a water pump, and a motor mount. Oh ya, and the tailight which was smashed unloading :pain: .

Lessons learned, if it ain't running make sure you get it really cheap and expect the worst. lol

I don't feel too bad, I was never underwater with the car, it would have been easy to part out and at least break even. These cars have a real following. While I was fixing this one went through salvage that had been keyed on both sides, had 50k more than mine and sold for more than I have invested.
 
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