I have an old 1985 Corolla with a SOHC '4A' Carb engine with a blown head gasket. I am replacing the head-gasket and wondering if they head bolts are reusable and not the stretch type.
My local parts shop didn't have any bolts listed for the engine and at the time couldn't ring around. Local Toyota dealer wants $20 per bolt. Trying to do it on the cheap but if they need doing ill replace. Thanks
a.woodrow,
Apr 29, 5:57pm
pretty sure they are tty and need replaced
ceebee2,
Apr 29, 6:03pm
Re use them no problems.have done so many times without incident.
morrisman1,
Apr 29, 7:15pm
I heard from someone that if the manual says "torque to X then 90° more" (or something to that effect) then they are stretch bolts.
rob_man,
Apr 29, 7:18pm
I think stretch bolts have the star/crown shaped heads and a stretch zone in the shank as well. Correct me if I'm wrong.
mugenb20b,
Apr 29, 7:29pm
$20 a bolt! The whole set is around $50. Ring your local engine reconditioner for a price or you can get them through Sta Parts.
thejazzpianoma,
Apr 29, 7:29pm
They are often torx, ribe, hex etc but not always. Some of the VW stretch ones look very much like regular bolts except they are a slightly unusual looking steel. What you say may apply to Toyota's perhaps!
BTW, on non-critical applications where you wish to take the risk and re-use a stretch bolt the tightening settings will be different. Generally you go with a torque setting only as opposed to the original torque + angle recommendation and use thread locking compound as well. Take this with a grain of salt as its a practice I avoid but have noticed it mentioned from time to time.
Personally, I wouldn't ever re-use stretch bolts on a head, the risk may be low but the stakes are high and the bolts are not usually very expensive at all.
Oh, and another clue as to whether the bolts are of the stretch variety in the case of an engine head might be whether the manual requires you to re-torque the head after some running or not. My understanding is that part of the reason for using stretch bolts in that application is to avoid the need to re-tighten as was common in the days of old.
rob_man,
Apr 29, 7:31pm
Yes, it's something I noticed while working on my Landcruiser motor.
thejazzpianoma,
Apr 29, 7:36pm
Good to know, I will remember that.
psx_man,
Apr 29, 7:43pm
I will replace them if they are defiantly stretch type. I'm going to rip off the head today or tomorrow so i guess once the bolts are out i can tell.
thejazzpianoma,
Apr 29, 7:55pm
Unlikely. as above they may look quite normal but still be stretch bolts. Someone must have a manual that will tell you though. Possibly even autodata.
realtrader1,
Apr 29, 9:03pm
Couldn't you get some high tensile bolts from the likes of Blacks Fasteners, of otherwise same specification but not stretch, and pop those in, instead!Surely they'd be cheaper and reusable: or am I missing something here!
floscey,
Apr 29, 9:23pm
Reuse the old ones there not stretch bolts .3 stage torque . 22nm-44nm-64nm . Remember to clean threads with wire brush and put a drop of oil on threads .
bellky,
Apr 29, 9:26pm
I don't know the answer but these speak to me.
msigg,
Apr 29, 10:08pm
They be alright, with that old motor.
pollymay,
Apr 29, 11:57pm
Reuse them, they are not true torque to yield bolts.
unbeatabull,
Apr 30, 12:36am
As above, 3 stage torque setting. Done a few heads on 4A Engines.
beast9,
Apr 30, 12:39am
if its the 4a with the spark plugs on the side of the head then no they are standed bolts if its the 4a with the spark plugs in the center of the head then yes they are torque to yield and have to be replaced
thejazzpianoma,
Apr 30, 1:11am
IF they were (and it seems they are not) that would be a terrible idea. The reason being part of the idea of the stretch bolt is that the stretch keeps a fairly constant tension (a bit like a spring) even if some settling happens between the tow parts. In the case of an engine head that negates the need for re-torquing the bolts. Also. they are not expensive anyway so its pretty pointless from that point of view as well. That's what you are missing. Just thought I would point this out in case someone reads this and gets "bright ideas" after reading your post. Sorry, not meaning to be rude.
realtrader1,
Apr 30, 1:31am
Thanks for that.The forum is for intelligent discussion and I like that. Forgive my obvious ignorance on this but. we haven't always had plastic deformation stretch bolts.Obviously, it would be a given that for an engine using conventional, old school bolts, you would retighten as per manu specs.Put price to one side.How can there be a problem with what I have suggested, using quality high tensile bolts and retensioning later!
bubbles244,
Apr 30, 2:06am
from seeing the turbo starlet guys at work the torque rating is "FT." most should know what that is. same with nissan blocks
pollymay,
Apr 30, 2:49am
They aren't TTY, they are more of a torque angle arrangement, you can reuse them and it's no big deal.
thejazzpianoma,
Apr 30, 2:54am
Top work on the mature attitude, I couldn't agree more with your comments about the forum.
Basically its a good idea to tread very carefully when changing a manufacturers design. Sure re-tightening helps, so long as the person is aware to do that. However those bolts also cope better with expansion and contraction due to heat, this may mean that regular bolts won't be up to snuff for the particular match of materials used in the head/block and gasket due to their expansion/contraction rates.
Plus. even if you work through all of that you then have to best guess the correct tightening torques and method as they will be very different with steel bolts.
At the end of the day its a lot of hassle and gamble for basically no payoff in terms of cost or convenience.
realtrader1,
Apr 30, 3:29am
Thanks.I think it's up to each of us to provide an example to one another.No need for albeit, concealed expletives either, for example.Yes, I know what you are saying and it might be a gamble.It might not be worth the risk.Then again, I will remain open minded on that one and talk to various people including metergolists.it's more of an interest factor than something I am confronted with as we speak. it's good to think outside of the square, but also come back to the square as a reference point!
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