1998 Mazda Protege LX with 1.5L What are the symptoms of a cracked exhaust manifold?

P

PhillyKorean

Member
:
1998 Mazda Protege
I have a 1998 Mazda Protege LX with the 1,5L engine and I noticed a small crack going across the Exhaust Manifold. I was told by the previous owner that because of that crack the car burns oil (even though the engine seems greasy and dirty), sounds loud like it is missing part of the exhaust(even though it has the entire exhaust), The entire car shakes whenever the car is idling (either at a red light or whenever the car is stopped) and it feels like the car feels like it is going to stall at any minute. Also it throws a flashing check engine light. I wanted to know if those are the actual symptoms of this car with a cracked exhaust manifold? What other damage do I anticipate?
 
if your problem is ONLY a cracked exhaust manifold...it shouldn't have any effect on burning oil...

a crack in the exhaust, depending on its location, can cause some funny stuff though...the system relies on pulse vacuum to help pull burned gas out of the chambers...a leak will ruin that vacuum, causing something known as exhaust reversion...in which pressure builds up in the wrong direction around the crack...the cylinders will 'push' the burned gas out, but the pressure gradient will stall it and try to push the exhaust gas back in...causing poor driveability, ridiculous idle, and hesitation in various rpm ranges...

depending on where the crack is...it can also interfere with the primary o2 sensor readings...making the engine mismatch fuel requirements in light load conditions and idle...making the problem even worse...

the bigger problem though...is possibly what caused it...I'm not sure on 98 models...but 99+ model ecu's only flash the ecu for sustained mis fire conditions...so its a p0300-304 code, meaning its misfiring non-stop...a mis fire will cause unburned gasoline to get inside of a hot exhaust pipe...in which it'll ignite there...and quickly burn up the manifold and/or catalysts...

first...fix the crack...replace the part, have it welded, whatever...while doing this, see if the catalysts check out...chances are they are now dead too; at least if you continued trying to drive with a constant misfire condition...if after the system is in check...you still get misfire problems...stop driving, you're just going to recreate the problem again...and i'd look into coils, plugs, wires, etc...to see what exactly is causing the misfire...

you may have leaking valves, or cylinder blow by problems that are causing the oil burning problem...and THAT may be whats causing the sustained misfire, of which eventually burned up your exhaust system...a crack by itself shouldn't blink the ecu constantly, and shouldn't do anything to oil consumption...it'll just drive like shat until you get it fixed, and may throw a solid code from time to time...but flashing...you have a lot going on it seems...
 
Last edited:
Ok from what I know the engine looks dirty and grimy I originally thought it is leaking from the valve cover gasket and being burned off, the crack is pretty much right before you get from the manifold to the flexpipe toward the bottom, I only said burning oil because when you start the car you can smell the burnt oil along with exhaust fumes from the crack in the manifold. They seller originally told me that they replaced the entire exhaust from the catalytic converter to the muffler. The flex pipe looks somewhat rusty but I can't see if there is a hole in that. I know that the exhaust manifold cracking was a common issue with the 2G protege (1995-1998) especially the 1.5L engine. When you accelerate the car sounds very loud and when you are pressing the brakes or idling in park mode you feel the entire car shake and the entire exhaust shakes too. I didn't go to autozone or to a mechanic to get the check engine light read yet, and I plan to do that soon. I also thought it was a misfire but I won't know that until I guess after the exhaust manifold is replaced.

.
Installshield 2 said:
if your problem is ONLY a cracked exhaust manifold...it shouldn't have any effect on burning oil...

a crack in the exhaust, depending on its location, can cause some funny stuff though...the system relies on pulse vacuum to help pull burned gas out of the chambers...a leak will ruin that vacuum, causing something known as exhaust reversion...in which pressure builds up in the wrong direction around the crack...the cylinders will 'push' the burned gas out, but the pressure gradient will stall it and try to push the exhaust gas back in...causing poor driveability, ridiculous idle, and hesitation in various rpm ranges...

depending on where the crack is...it can also interfere with the primary o2 sensor readings...making the engine mismatch fuel requirements in light load conditions and idle...making the problem even worse...

the bigger problem though...is possibly what caused it...I'm not sure on 98 models...but 99+ model ecu's only flash the ecu for sustained mis fire conditions...so its a p0300-304 code, meaning its misfiring non-stop...a mis fire will cause unburned gasoline to get inside of a hot exhaust pipe...in which it'll ignite there...and quickly burn up the manifold and/or catalysts...

first...fix the crack...replace the part, have it welded, whatever...while doing this, see if the catalysts check out...chances are they are now dead too; at least if you continued trying to drive with a constant misfire condition...if after the system is in check...you still get misfire problems...stop driving, you're just going to recreate the problem again...and i'd look into coils, plugs, wires, etc...to see what exactly is causing the misfire...

you may have leaking valves, or cylinder blow by problems that are causing the oil burning problem...and THAT may be whats causing the sustained misfire, of which eventually burned up your exhaust system...a crack by itself shouldn't blink the ecu constantly, and shouldn't do anything to oil consumption...it'll just drive like shat until you get it fixed, and may throw a solid code from time to time...but flashing...you have a lot going on it seems...
Click to expand...
 
tune up, check for leaks by cleaning the surfaces of they engine where suspect leaks are with carb/brake cleaner. You will notice very quickly where the leak is comming from.

and

finding the leak is easy just follow your hand closely over the exhaust DONT TOUCH IT, and feel for a "puff" of warm exhaust gas when the engine is idling and its simple as that. sometimes a leak will be visually spotted out as black soot on the exhaust where the leak is.

AND

when the light flashes its because there is a missfire, the light blinks bc your dammaging your cats (due to the heat that builds up when raw fuel is dumped into the catalyst.

you do have alot of issues but it all sounds like a poorly maintained car that is overdue for its fair share of maitenence, i say that you should address the blinking cel first bc burning up a cat destroys performace, and they typically are pretty pricey to replace.
 
Yea I bought the car knowing it needed work but I was suprised that it needs a s*** more work, now I may be starting to suffer from buyers remorse lol. I guess all i can do it replace the exhaust manifold first to eliminate the new catalysts I will be putting on. I am new to the protege's 1.5L engine is the catalysts on the exhaust manifold or is it further up or down?
it seems like getting a new engine and swapping it out might be cheaper but how much does a decent 1.5L engine or even the 1.8L engine run for when you buy the entire engine? is it more than 500 or 600 for the engine and like another 1000 for labor?
 
i know you dont have a whole lot of experience but i would figure fixing the engine would be a lot cheaper. Have you ever took it in to have I looked at by a qualified tech? if its got a s*** ton of miles then yeah get a new engine but im sure you will easily be 2grand in for a used engine to be installed (prob high miles too)

it would be WELL worth your time to take it in and possibly only have to spend a couple hundered
 
I was told by a senior member who seems to know his stuff that if I am only having to refill the oil every 1500 miles or so I am good but if I have to refill 1qt every 600 miles that's NOT good.

Well unfortunately I was able to get a hold of the previous owner and according to her, She will top off the oil, every 500-700 miles, also all her oil changes and oil preference was synthetic only. She also told me she used the fuel treatment/ fuel injector cleaners by lucas and stp every 2000 miles. Also something I saw that was weird was when I first saw the car at the seller's place I noticed a burnt and ripped wall power cord (the one with 2 prongs and the round ground prong) to plug into a house wall. I asked the seller about that and she said that the owner before her lived in a very cold area and had to plug in a engine block heater into the wall to keep the engine from freezing temperatures. I am still not sure why the hell the ripped power cord is there and if that might play any role in the car acting the way it does aside from the exhaust manifold crack.

The previous owners mechanic told them that the oil burning is due to old age like a bad valve cover gasket or oil filter.
that is the forum where the senior member told me about what I should do with the car.
http://www.mazdaforum.com/forum/maz...what-symptoms-cracked-exhaust-manifold-31199/
 
Last edited:
First off valve cover gasket is $20 and takes 10 minutes to replace, oil filter should be changed with oil so if its causing it to burn oil somebody should be smacked in the face with a cactus for not changing it. That "mechanic" sounds like an idiot

With high mileage engines you don't want to use synthetic oil as it will burn faster, just use conventional penzoil
 
Please log in or register to reply here.

Similar threads

J
Need info on upgrading MSP turbo, exhaust manifold and down pipe
Replies
3
Views
3K
SavagePk
SavagePk
Y
Cracked exhaust manifold
Replies
5
Views
2K
BOOSTR
B
D
Need help with turbo and exhaust issues
Replies
2
Views
2K
jeffmsp
J

Latest posts

Back