Common vacuum leak points?

jsilva said:
If there was a leak from the cylinder to one of the jackets wouldn’t there be another sign? Especially if the leak is so bad that there is no compression? Seems to me I’d either be burning coolant or possibly getting dirty coolant. I’m no expert though.
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You are correct to be suspicious of other symptoms, but with the information you have provided it is difficult to draw a conclusion. As you have confirmed you have compression in the other 3 cylinders, which tells us your testing process was successful. The following question is why is cylinder 4 showing 0 PSI?

The next step is usually a leak down test if nothing else is obvious, as you are experiencing in your case.
 
Well the adventure is over. I was driving maybe 5 mph and heard a loud sound and heard pieces falling to the road. I‘m guessing the engine threw a rod...:)

B8132B86-3F75-4468-9084-497B2C5863AC.jpeg

Interesting, the hole is on the timing cover side of the engine around the top of the oil pan. I assumed if any rod or bearing broke it’d be #4 since that’s the one having issues. What’s the likeliness it’d bounce off the oil pan but then break the block? I won’t know for sure until I take off the oil pan.

Guess this combines all of my other issues into one ... I have to get a new engine now! :) Too bad I don’t have the money for it right now.
 
Well at this point why even take off the pan to see what failed? Its complete engine failure so unless yours is automatic and you need to access the flex plate bolts just pull the engine and throw another in. My speed 3 had thrown rod number 4 through the block which is why I purchased it so cheap. Save up some cash and get a replacement motor. You may get lucky and find one with a few upgrades on it already.
 
L337TurboZ said:
Well at this point why even take off the pan to see what failed? Its complete engine failure so unless yours is automatic and you need to access the flex plate bolts just pull the engine and throw another in. My speed 3 had thrown rod number 4 through the block which is why I purchased it so cheap. Save up some cash and get a replacement motor. You may get lucky and find one with a few upgrades on it already.
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Yes you’re right. I’m interested in knowing specifically what happened but I might as well start pulling apart the engine. I’ll probably dismantle it over time just to get some experience with things like the pistons, rods, and bearings, since I’ve never done anything with those. It’ll also make the engine less heavy :)

I got this one cheap too, which is why I bought it. I thought worst case I’d eventually need to get another motor. Looks like worst case is now. It has a nice suspension which is lowered and really awesome to drive around corners, so I’m bummed it’s out of commission for now.
 
It was a ticking time bomb. I wouldn't draw any conclusion that because #4 had low compression that it was the one that failed. I bet when you pull it apart, it will be something closer to the area where it broke through the engine, such as rod #1.

As to why it happened: could be a number of things, but if you are running fully stock, you could have loaded it too hard (6th gear flooring), it had a miss fire that was just too much for the already stressed engine and your rod turned into shrapnel.
 
The_big_dill said:
It was a ticking time bomb. I wouldn't draw any conclusion that because #4 had low compression that it was the one that failed. I bet when you pull it apart, it will be something closer to the area where it broke through the engine, such as rod #1.

As to why it happened: could be a number of things, but if you are running fully stock, you could have loaded it too hard (6th gear flooring), it had a miss fire that was just too much for the already stressed engine and your rod turned into shrapnel.
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I think you’re right in that it was #1. But we’ll see. I’ll start taking it apart tomorrow.

I actually was going very slow when it happened! 5mph in 1st gear after turning at a stop sign with light acceleration :) I left a trail of oil until there was space on the side of the road to park.
 
Enki said:
Speaking of oil, what brand/weight was it?
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I had been using Rotella T6 since I got it. I think I did 3 oil changes since I finished replacing the head gasket last Dec.

I also used Engine Restore. Actually, come to think of it, I did the CRC Motor Treatment added to the crankcase for 50 miles followed by an oil change. And I did another oil change after that one.
 
Enki said:
That could be part of the problem. If you've got time, some suggested reading:
https://mazdaspeeds.org/index.php?t...a-scratch-n-sniff-discussion.4603/#post-67081
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Thanks Enki! I read through the thread and watched the second video. I’m assuming then that the Rotella T6 has a higher calcium content?

I actually had been having detonation while the car is warming up, and it tended to buck a little bit too during warm up (I was guessing the cylinder misfire but the check engine light wouldn’t newly flash). So sometimes I’d press the accelerator a little harder to get the rpms above 3000 which made it run much smoother during warm up. It is more than possible I did this when the issue happened but I don’t remember. However, the car had only been running for maybe 2 minutes. Would it be hot enough after 2 minutes to cause a super knock?
 
Quite a few completely stock cars blew up getting off the highway, which was described in the podcast as being from LSPI. Funnily enough, tuned cars don't have this issue (because they are generally leaned out a bit and have timing added, reducing fuel washdown issues).

Did you have actual detonation you could hear or were you just seeing KT on your logger? These ECUs like to report KR when it's really just a timing adjustment (at least under light loads).


Per the UOAs in the following thread, the additives look *okay* but the good ones are low to nonexistent and the flashpoint of the oil is fairly low, so I certainly wouldn't run it (nor do I).

https://mazdaspeeds.org/index.php?threads/uoas-used-oil-reports-lets-see-em.5060/
 
Enki said:
Quite a few completely stock cars blew up getting off the highway, which was described in the podcast as being from LSPI. Funnily enough, tuned cars don't have this issue (because they are generally leaned out a bit and have timing added, reducing fuel washdown issues).

Did you have actual detonation you could hear or were you just seeing KT on your logger? These ECUs like to report KR when it's really just a timing adjustment (at least under light loads).


Per the UOAs in the following thread, the additives look *okay* but the good ones are low to nonexistent and the flashpoint of the oil is fairly low, so I certainly wouldn't run it (nor do I).

https://mazdaspeeds.org/index.php?threads/uoas-used-oil-reports-lets-see-em.5060/
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Actually I mistyped ... I was having delayed detonation or back fire when the car was warming up. Perhaps too rich a mixture for whatever reason (I assumed the misfire on #4). Not terribly loud but audible.

I had read many threads and reviews from others saying how great Rotella T6 is. I have a few 5 quart jugs still. Maybe I can use them in another car with a zinc additive.
 
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