How to replace cylinder head gasket - 4Y?

Some useful articles on doing it yourself
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Jaco Versfeld
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How to replace cylinder head gasket - 4Y?

Post by Jaco Versfeld »

Hi there,

How do I replace the cylinder head gasket? Do I need to remove the tappet cover - in order to get to the bolts of the cylinder head?

How difficult is it to replace the valve stem seals?

How much should I torque the bolts of the cylinder head after I am done (after the cylinder head has been skimmed etc.)

I first have to do some extra contract work (scheduled in 3 -4 month's time) before I can acquire a replacement engine. In the mean time, I thought I might get the engine in a running condition - if the pistons and crank is still in an o.k. condition.

Where is the thermostat? Can I replace it without removing the engine?

What else should I look out for?

Thanks,
Jaco
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Re: How to replace cylinder head gasket - 4Y?

Post by Mr_B »

Hi Jaco,

Replacing the head gasket on a 4Y is a pretty simple job, but if it is to last it must be done properly. Also doing the headgasket may not be a difficult job, but it would be a complete waste of time if don't first find out why the head blew, like head gasket failure(old age,deterioration), stuck thermostat, cracked head, blockage in the radiator, broken viscous coupling , etc. If the problem was more than just head gasket failure from old age, then the cause must first be addresses and fixed first.

A basic step by step rundown of the job, please note I may have forgot a step or 2, so any input is welcome:

1. drain the coolant in the block, the drain plug(bolt) is just behind the alternator, below the exhaust manifold.
2. drain the coolant in the radiator by removing the bottom pipe, disconnect the water pipe coming from the back of the head, disconnect the water pipe at the top(between the radiator and head).
3. drain the oil via the sump plug, with a blown head the oil may be contaminated with water. Remember to put the sump plug back, or you may land up wasting 5 litres of new, clean, expensive oil(been there, done that!)... remove and toss the oil filter!
4. loosen the bolt on the powersteering pump pulley, before removing the belt.
5. remove the powersteering belt and alternator belt.
6. remove powersteering pump pulley bolt and carefully wiggle the pulley off the shaft.
7. behind this pulley are 2 bolts, remove them, as well as the one at the rear of the pump steering pump. This should loosen the PS pump from the mounting bracket, carefully remove the PS pump and place it on the chassis below(upright, so it doesn't leak). Secure it there with a piece of wire, so it can't fall off.
8. Remove and the carb linkages, disconnect the electrical plug, disconnect the fuel pipe, disconnect the vacuum pipes(take note/take pics so you know where each vacuum pipe goes for re-assembly), remove the bracket holding the accelerator cable, remove the 4 nuts holding the carb on the intake manifold, remove the carb.
9. Loosen the bolts holding the exhaust and intake manifold in place (can be a pain the get these bolts loose, may want to spray them with a penatrating oil first). Remove the intake and exhaust manifold. You may have to disconnect the header-exhaust connection to remove the exhaust manifold.
10. Unbolt and remove the tappet cover.
11. Unbolt the rocker shaft, each bolt little by little so the shaft is lifted evenly, remove the rocker shaft, the pushrods can be removed one by one, again mark where they came from so they can be returned in the same position.
12. Using a power bar or the like, loosen the head bolts one by one, 5 of them are under the tappet cover. Remove them and mark where each one came from so they can be put back in the same place, also be careful not to leave the washers behind.
13. Under the ignition leads on the head, are 3 bolts holding the head in place, remove them.
14. The head can now be removed.

Assembly is basically the reverse of this process. Have the head checked and skimmed before starting re-assembly. You will need a new head gasket(use the orginal Toy one or a Payen one), a intake/exhaust manifold gasket and some decent gasket maker.

The most time consuming aspect of the job is cleaning all the bits and pieces, and carefully cleaning the mating surfaces on the block, head and exhaust/intake manifolds.

On torqueing the head bolts, once the head is back on, the bolts should first be torqued to 30nm each in sequence(I'll get the sequence from the workshop manual this evening), afterwhich they must be torqued to 90nm again in sequence. You will need a good torque wrench for this job. The head bolts must be re-torqued to 90nm at 1000km.

The valve stem seals will have to be replaced by an engineering firm as special tools are needed, like a valve spring compressor.

The exhaust/intake nuts will probably have to be replaced, as well as the nuts and bolts on the header-exhaust joint.

The thermostat is in an awkward spot, it's in the housing behind the alternator/PS pump, where the lower water pipe from the radiator connects to the engine, it is easier to access with the PS pump out the way.

Super experienced 4Y Hilux fundi's like Simoan and Allan will probably give more advise!

B
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Jaco Versfeld
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Re: How to replace cylinder head gasket - 4Y?

Post by Jaco Versfeld »

Hi Bretton,

Thanks a lot for the info. Do you maybe have the sequence of how the bolts should be fastened?

Which manual are you referring to?

Kind Regards,
Jaco
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Re: How to replace cylinder head gasket - 4Y?

Post by JohanM »

Jaco, I think Bretton is refering to the Haynes workshop manual!!!

I will have a look tonight and see what the sequence is for removal and fastening of the cyl head bolts. I will then try and upload a diagram.....
Johan Marais
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Re: How to replace cylinder head gasket - 4Y?

Post by Scooter »

Bolt sequence.JPG
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Re: How to replace cylinder head gasket - 4Y?

Post by Mr_B »

Thanks Scooter, I actually forgot... :oops:
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Jaco Versfeld
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Re: How to replace cylinder head gasket - 4Y?

Post by Jaco Versfeld »

Thanks everyone

Kind regards,
Jaco
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Re: How to replace cylinder head gasket - 4Y?

Post by Scooter »

No worries.

As you can see from the pic, you start from the middle and work your way outwards. This will apply to just about any head you want to tighten including your own :twisted:
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Re: How to replace cylinder head gasket - 4Y?

Post by KZET »

Hi There

I have a 3l KZTE D/C 4*4 2001 Model,with 153000km on the clock.

Recently I noticed that the radiator runs dry,but the water runs into the waterbottle.If the bakkie idles the water pushes our of the radiator.

I took a trip to Cape Town twice from Montagu,but the temp. stayed constant.

Any advice where to start looking for the problem.

Regards,

KZET
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Re: How to replace cylinder head gasket - 4Y?

Post by Mr_B »

Hi there,

I'm not clued up on the KZTE, and getting it wrong on that motor is uber expensive... I would advise you to contact Allan of AEW, he is hilux mech and owns a KZTE himself... his username on the forum is Hoppie... 072 127 1160

B 8 )
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Re: How to replace cylinder head gasket - 4Y?

Post by Mr_B »

Oh one pointer... it is possible for a crack to occur between the water channels and oil side of the block... in this case coolant(under higher pressure) would get into the sump(lower pressue) and mix with the oil... pull out the dip stick and check that the oil is clear, not like a milkshake(creamy and aerated)... if it is... do not attempt to drive to vehicle as major engine damage will result!

B :Geek:
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Re: How to replace cylinder head gasket - 4Y?

Post by Mud Dog »

Water in oil or oil in water indicates a breach between the oil and water galleries and this could be in any number of places, most often head gasket.
Recently I noticed that the radiator runs dry,but the water runs into the waterbottle.If the bakkie idles the water pushes our of the radiator.
From what you're saying it sounds like the motor is compressing into the water jacket, so displacing the water with air. Almost certainly a gasket problem, but as Bretton said, why!? There is more than likely an underlying cause. Could even be a cracked head, or less common, a cracked block.
Either way, the problem is serious enough that you should not use the vehicle till it's fixed.
Hope it's not too costly, good luck.
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Re: How to replace cylinder head gasket - 4Y?

Post by Scooter »

Perhaps look at bleeding the coolant system before you jump to blown heads. If you have run it dry for whatever reason and replaced the coolant, there might just be an air lock in the system.
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Re: How to replace cylinder head gasket - 4Y?

Post by Riceburner »

Jaco you can bring your hilux to me, I will do it for you.
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