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Mazda Engine General \  dumb question but i need an answer

dumb question but i need an answer

Mazda Engine General Mazda Engine Mazda Tech
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replies 14
following 8
 
neptune   +1y
so.. some of you may remember im having some pressure problems in the cooling system after a head gasket change, i realized that it was not clogged after doing a full flush.. with a garden hose lmao. it worked and the system went through just fine. so yes there is pressure coming from the pistons somewhere and i got to thinkin.. duh i know exactly why, when i gave it to my dad he drove it home.. before the gasket was changed.. so im 89% sure the head bolts are stretched from him driving it. my question is do i have to drop a bill on these new or can i hit the local pull a part and get them used????

btw im a cheap a$$ and the im pushing more for the used ones but i was told i can not use bolts off of another truck?? cuz it wont torque right.. and will be like they are now.
maztang (ryan)   +1y
you have to replace them with new bolts. i asked the same question when i rebuilt my engine. the bolts stretch when you torque them and therefore can not be reused. i bought mine from cheaper than anywhere i can find them locally.
beatmymini   +1y
head bolts stretch just from you loosening and retightening them so getting some from a junk yard wont help you at all. get new ones.
mazdatweaker   +1y
I have rebuilt more of these motors than I can count on a bunch of fingers.

I have NEVER had to replace head bolts on either 2.0 or 2.2 motors.

They are not stretch to torque anything.

The engines are low-compression tractor motors.

Anyone who is telling you they need to be replaced is a member of the

1. I did it, so you have to do it club, or,
2. don't know any better, or,
3. was sold that story by somebody else.

If you used a tap to clean out the bolt hole threads when you had it apart, and cleaned the threads on the bolts, and oiled the threads before putting it together, you should have been OK.

At 5,000 miles, the bolts MUST be re-torqued, to compensate for the gasket crush which occurs once the engine has reached operating temperature a few times and the aluminum head has expanded from the heat of use.

I noticed you indicated that: "it wont torque right"

And that might be because of thread bind due to corrosion left from the prior gasket R&R. Or material, like oil, antifreeze or old gasket debris, was left in the bottom of some of the bolt holes, so the bolts are running into it.

added edit:

I found this series of posts with DETAILED information about re-torquing loose head bolts.

neptune   +1y
cool thnx for the info, ive re torqued it 3 times, once when i first put the head on. then once after it ran the "break in" time, then i ran it for about 45-60 minutes then torqued them hot. and these ones torque fine thats just what the guy at napa told me, said the used ones wont torque cuz they would be stretched lol and they are 95.99 for the set... i was like are you kiddin me, 12 bolts cost me $100 you must be crazy HAHAH

i did not do a cylinder compression check tho so i dont know if they would show up low if it was leaking into the coolant, should i check it with the rad cap off??
jmzcustomz (jeff)   +1y

LOL Gotta be one of the funniest but true statements yet. Not so much tractor but I have been on MANY fork trucks with damn near the same motor...running propane. LOL Oh come on tweaker you the whopping 65hp can easily blow that head right off of there....with some C4.
immortal1 (linn)   +1y


LMAO as well Jeff. Tweaker hit the nail on the head with that line. As for the C4 I don't think so.... but I bet a 250hp shot of nitrous would do it LOL. Honestly the funniest thing I run into with my truck is all the "uneducated" people that think I have 4 nitrous tanks in the back. I mean come on people.... The hoods open and it's obviously a 4 cylinder under there. I really don't think the poor motor is gonna handle a nitrous "pump" connected to each cylinder

Anyway, I agree with Tweaker on this one. I have had the head off 3 of these motors and never once replaced the head bolts. And the 2 motors I currently have running (purple truck and green truck) run just fine. Well, as fine as a tractor motor can be.

Good luck with your project NeptunE!
canucksfan1   +1y
Yeah i am pretty sure the head bolts are not torque to yield so u should be ok running the old bolts, just make sure you clean out the threads in the block
neptune   +1y
ok sweet thnx guys!!! im gunna pull it off and replace the gasket again, ill blow it all out with my compressor and a wire brush. one thing i should note is the crackhead that did the headgasket just before i got it lined the whole driver side down with silicone LMAO but i cleaned it off so maybe there is some in the threads.. i hope its an easy fix thanks again you saved me $100
mazdatweaker   +1y
[sort of quoting="NeptunE"] what the guy at . .the . place where they keep the doors open by selling parts. . . told me, said the used ones wont torque cuz they would be stretched and they are 95.99 for the set... i was like are you kiddin me, 10 bolts cost me $100 you must be crazy . . .[/quote]

Thank you for proving my point.

[again quoting="NeptunE"]i did not do a cylinder compression check tho so i dont know if they would show up low if it was leaking into the coolant, should i check it with the rad cap off??[/quote]

If you can get your hands on a coolant system pressure checker. . . via a "loan-a-tool" program . . there is a really good way to check for a pressure problem in a block.

With the engine off and the water jacket full, install the pressure checker. Have someone else start the engine. If the pressure jumps immediately, there is probably a gas leak into the water jacket.

If the gauge needle fluctuates (pulses). . . there is definately a gas leak. At that point, with the engine running, you can disconnect one plug at a time and that will tell you which cylinder is pumping gas pressure into the water jacket. The pulsing will stop.

If you don't have a pressure tester, you can leave the radiator cap off, with the engine idling. If you see air bubbles at the filler neck, that is usually a sign of a gas leak.

I would take the head to a machine shop and get it pressure checked for cracks if you are taking it off as insurance that it isn't bad or cracked internally. Crackheads and cracked heads usually go together like sillyconehead glue and headgaskets.

One last thing. . . and it's listed last because it is the one thing that anyone who reads this needs to take away because it is so important. . .Use a tap to clean out the thread holes. . .it realigns the threads and cleans off any burrs that a brush can't and won't.

One thing I have learned with these rebuilds is that you either do it right or you do it over.