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Old 08-25-2016, 12:43 PM   #1
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Default why do I keep blowing head gaskets?

Guys im getting to the point where a v8 is sounding like a good idea just for reliability... i just blew my second head gasket this summer...
Just an fyi thorugh this I am running ARP head studs torqued to 70 ft/lbs

the bottom end is built with manley rods and super tech 8.6:1 pistons
the deck surface was not flat with .0015 feeler guage being the biggest one I could fit under my straight edge, to me that seems acceptable but maybe not?
also the deck surface cleaned up really well with you only being able to see the ring from the oem gasket around each of the cylinders, you can not feel the ring just visually a difference in color where the ring is.

the head is what i believed the problem was... first time i blew the head gasket it burned a bit of coolant in cylinders 1 and 4 "i tested this by pressurizing the cylinders and watching coolant bubble up through my radiator"

I had machined flat before I installed it the first time but the finish didn't look good enough to me. it ended up blowing that head gasket...

so I sent it out to a shop that is known to do MLS gaskt surfaces, the finish was much better I got 40-60 RA with a RA meter

I put that head on the car and it fired right up and sounded good and I let the car go through three heat cycles before I started to get on it. the car runs off of e85 and im running a fairly conservative timing map so i dont believe there was detonation, didn't feel any hesitation or hear anything. the AFR's looked good "a little on the rich side" but I still did some tuning anyways to dial them in a bit closer to the target ".78 lambda" under boost.

but after about three pulls running through the gears the head gasket blew again!!!
I have always run oem mazda gaskets because iv been told they are the best.

would you recommend cometic gaskets?

i called flying miata who sold me the turbo kit and they told me that even if my head is flat when not torqued down that it could still be warped when its torqued down and that i should find a head that has not been overheated.

what are your guys opinions? i would like for my car to not blow up all the time! i have no idea what im doing wrong so please if you see anything please point it out! at this point i will literaly do anything just to make my car run right, if i have to build a tubular k member and put a ls motor in it i will but i think its way cooler to have a 4 cylinder making the power that i want to make which is about 350 hp

thanks for the help guys, i need it!

Don



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Old 08-25-2016, 12:56 PM   #2
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Torque sequence? What wrench, and is it calibated? Are yiu using the ARP grease on all surfaces? Are you using the Mazda thick washers with the ARP studs? The ARP ones were shrimpy and I didn't like them. How much boost?
Head could have a cracked seat, or a crack somewhere. Has it bean checked?
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Old 08-25-2016, 01:04 PM   #3
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Torque sequence? What wrench, and is it calibated? Are yiu using the ARP grease on all surfaces? Are you using the Mazda thick washers with the ARP studs? The ARP ones were shrimpy and I didn't like them. How much boost?
Head could have a cracked seat, or a crack somewhere. Has it bean checked?
im using the torque sequence out of the haynes manual that i have. i start at 20 ft/lbs the go to 40 ft/ lbs then to 60 ft lbs then to 70 ft/ lbs. I use the arp grease on the washers and nuts and the tops of the studs "the bottom of the studs i clean with break cleaner before i put them in the block." however I'm not using the mazda washers, i have them so i can use them on the next head.

as for torque wrench I'm using a beam style torque wrench that i have had for my whole life, i also have a click style torque wrench but i had been told in the past that beam style torque wrenches are the best?

head has not been checked with dye for cracks but i have done some pretty extensive visual inspection... the original head i had was cracked between the cam shafts letting coolant seep up into the oil.

Last edited by JacksonRacingEngines; 08-25-2016 at 01:08 PM. Reason: forgot to answer a question
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Old 08-25-2016, 01:12 PM   #4
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you're doing 70ft/lb on greased ARP's? umm, there's a good chance you cracked your head
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Old 08-25-2016, 01:13 PM   #5
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you're doing 70ft/lb on greased ARP's? umm, there's a good chance you cracked your head
what torque spec should i run with greased arp head studs? i have no problem purchasing a new head, i wanted to upgrade to an nb head anyways.
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Old 08-25-2016, 01:16 PM   #6
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we have a thread specifically about this. check it out

I think the final consensus is somewhere between 50-55 or something.

arp's clamp way harder. greased arp's even harder. you can crack your head
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Old 08-25-2016, 01:19 PM   #7
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we have a thread specifically about this. check it out

I think the final consensus is somewhere between 50-55 or something.

arp's clamp way harder. greased arp's even harder. you can crack your head
haha well I know i can crack my head, I cracked one already... this would be my second if it really is cracked... I will look at that thread, thanks for the information on that, it could be exactly the problem.
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Old 08-25-2016, 01:28 PM   #8
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I would also calibrate the clicker against the beam. Then use the click. The major problem I have with the beam type, is the parabola effect when not looking straight down on the needle. And our perception of what is vertical. Parabola, is that the right word?
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Old 08-25-2016, 01:37 PM   #9
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I would also calibrate the clicker against the beam. Then use the click. The major problem I have with the beam type, is the parabola effect when not looking straight down on the needle. And our perception of what is vertical. Parabola, is that the right word?
i can do that, never thought to do that but seems like a good idea, i always tried my best to make sure i was reading the needle from directly above but its not a whole lot of fun so i can try calibrating the clicker with the beam style one and then use the clicker.

where would you guys recommend getting a good used head? I have the ability to disassemble it and get it machined if needed...
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Old 08-25-2016, 01:45 PM   #10
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18psi what head gasket do you have in your car? oem mazda?
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Old 08-25-2016, 01:47 PM   #11
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OEM MLS. always
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Old 08-25-2016, 01:48 PM   #12
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OEM MLS. always
thanks!
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Old 08-25-2016, 01:55 PM   #13
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I use MLS from eBay and they run about $25-30 depending on the time of the year and such. Never had an issue with them and I cannot tell the difference between them and an OEM one from Mazda.
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Old 08-25-2016, 01:58 PM   #14
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ARP's most recent torque spec is 65ft.lb with a much larger washer (just a hair larger than the OEM washer) included in the kit. Not sure when they switched to this spec, I just noticed in the last box I opened from them. I've been torquing to 65ft.lb for years, so 70 isn't going to hurt anything. 80 might.

If you've ever had to take more than ~.005" off your cylinder head due to warpage, you were supposed to have it straightened in an oven first. I would replace the cylinder head, since it sounds like it's been nuked a few times.

These motors do not blow head gaskets normally. It's a closed-deck block, MLS gasket, and we use good fasteners. There are 400-500whp cars running stock MLS gaskets and ARP studs, so it's not inherent to the platform.
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Old 08-25-2016, 02:14 PM   #15
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Quote:
Originally Posted by ryansmoneypit View Post
I would also calibrate the clicker against the beam. Then use the click. The major problem I have with the beam type, is the parabola effect when not looking straight down on the needle. And our perception of what is vertical. Parabola, is that the right word?
I believe you mean the parallax error.
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