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Headgasket????

willthompson

Active Member
Joined
Nov 5, 2018
Messages
96
Hi guys

Just making a shopping list of parts to go through my 1hdt with and i will be doing the headgasket but there seems to be 3x thickness or notches, does anyone know which one i should be putting on it or anyway to find out.

Cheers
 
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On the original gasket there should be a mark (notch) on the corner next to No. 6 cyl which denotes the thickness.
If the engine has been fully rebuilt, the piston protrusion from the top of the block should be measured and the appropriate gasket selected. If it's only the head that's been off and it's not been skimmed then I guess you could just use a replacement gasket identical to the old one bearing in mine there are 5 different thicknesses used at the factory but only 3 available as replacements. This is from the FSM for the 1HD-FT, not sure if the gasket numbering is the same for the HDT.


Gasket No. 1. 0,225mm or less

No. 3. 0.226 to 0.325mm

No. 5. 0.326mm or more
 
Head has never been off as far as i know, its only done 140k but i have been getting a little bit oil in the rad but i have done a manual swap so it does have the auto rad on it and its loosing pressure ever so slightly so i think its sucking oil out of the cooler (which i believe is the original as well) but i am just going to go through the whole thing with gaskets/headstuds/belts etc and a new rad.
 
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i have found the notches, I am on 3x didn't realise they where so visible.

thanks
 
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Most rebuilders just fit number 5.
 
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have the head skimmed and fit a number5?

thanks
No, stick with the original thickness. it will lose compression and not go aswell. unless the head is warped which i doubt it is. i wouldnt skim it either. you are taking life out of the head (remember its cast iron not aluminium). check the head with a precision straight edge. if in spec clean the head and leave it alone. you must use a genuine headgasket and bolts though no exception. you supposed to measure the piston protrusion to determine head gasket thickness. so unless you are decking the block too or changing the pistons you always stick with the original thickness of head gasket. even if you do have the head skimmed the proper way to do it is to drop the valves back too. not just fit a thicker head gasket. 3 notch is common and they go really well on this thickness. rare you see 5 on a 1hdt.
 
thanks for this

Yes i have oem head bolts and washers in my order all ready do not worry doing all new oem engine gasket kit as well and new valve cover bolts and washers + timing belt and and all pulleys and gears.
 
have the head skimmed and fit a number5?

thanks
a good number of reputable builders will use a number 5 even if the head doesnt need skimming. its considered the size difference in gaskets and the lowering of compression to be negligible. a bit like some will use a plasti gauge and fitted BEBs and others use one standard size i suppose..

personally i would measure piston protrusion before fitting the same size gasket.

make sure you have a decent bar for the +90 +90 on the head bolts, gets a bit tiresome, i mark them with a marker pen rather than trying to use a angle gauge.much easier and you cant lose track of where you have been.

clean out the threads, a lot of crap can collect in there.

i think i would see if changing the rad solves the problem before taking the head off. sure its not just residue oil?
 
I just used the old bolts. Yes clean out the threads in the block. You can crack the block if you have oil down the hole and screw the bolt in. Done that once.
 
I just used the old bolts. Yes clean out the threads in the block. You can crack the block if you have oil down the hole and screw the bolt in. Done that once.
No good if your running a big turbo or boost. You must use new toyota bolts. If you are running stock turbo pressures you will get away with reusing the old bolts.
5 notch on stock machined surfaces definitely drops sharpness of engine. Stick with what comes out unless you start to machine things or swap pistons out.
 
I just used the old bolts. Yes clean out the threads in the block. You can crack the block if you have oil down the hole and screw the bolt in. Done that once.
Plus one on cleaning threads out. This is a must
Remember to lubricate the threads lightly too and don't forget the washers these are really important.
 
I know in the 1KZ manual it actually shows a diagram where you can measure the "stretch" on the bolt and IF they haven't stretched beyond toyota's limit you can reuse them. I've done so without a problem.
 
i wouldn't just use the no5 head gasket... much better to do your own measurements on the protrusion of the pistons off the block deck. Then to use the appropriate gasket thickness as by the FSM... As always follow the FSM step by step as you do this kind of work.

Be a right shame to have a lower compression engine because the head gasket is the incorrect thickness..

It doesn't matter if reputable people just fit the no 5 gasket..... you're doing the job and for the best result... do your own measurements and fit the correct one!

Head bolts are duff if they're over stretched and too long....if in spec of length then it's upto you to buy new or reuse.... at you're own risk!
 
You can also use original con rod bolts too if they measure up.

The risk factor rises, Frank risky risky!!

When you think about this.... the one size BEB'S that fits all, is the same line as just fitting the 5 notch head gasket!! There are 5 original sizes of bebs and have ended up thinking there's no1 3 5 available ... same as the 5 sizes of head gaskets that coinsidently are available in 1 notch 3 and 5 respectively..

Why settle for no5 when you could need no 4? Lol!

And that's presuming that there's only 1 cylinder that requires the bigger sized gasket! :thumbup:
 
Iwan, the factory manual is pretty cautious but they say you can use the old bolts if they measure OK. Everything will break in the end but the bolts have a massive lifespan. You could buy a faulty bolt that snaps immediately. At least old bolts have been tested.
 
I agree with you Frank. I reacted to the comment that you can't reuse the bolt's and to just fit the biggest head gasket... follow the fsm and check the piston protrusion on all cylinders... then you have the correct head gasket. Sorry for wrecking the thread folks.
 
Oh, I always torque up twice, you'll see why..
Do the first run as per fsm, then go over them again as per fsm.
I also lube both sides of the washers.
 
I mark my bolts with centre punch after first pass.
1. To ensure each has been turned on the second pass.
2. To see they are all tuned 90 degrees.
 
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