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Head Gasket Replacement, 1984 Nissan 720 w. 2.4l 4cyl engine


foxfan1992

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Hey guys. I just bought a reconditioned cylinder head for my 720 truck, and a new head gasket set. Does the head gasket go on bare, or do I need any sealant like hylomar or hermetite? Any tips on what I should look out for while fitting it all together?

 

I know I have to follow the head-bolt tightening sequence and I have everything stored the way I took it off - so it all goes back together in the same order.

 

I can't find the correct torque settings for the head bolts or cam sprocket bolts in the Haynes manual, is there an online manual I can download?

 

Thanks

Harry

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No sealant, but head and block surfaces must be absolutely clean for good long lasting results.

 

Aluminum heads can warp so check with a straight edge.  You are allowed 0.004" of warp along the length. Never hurts to check... you can send back now instead of later.

 

Head bolts are re-usable but must be spotlessly clean as well as the bolt hole threads. Wipr bolt threads with oily rag and put a drop of oil under the bolt head against the steel washer.

 

Head bolt tightening pattern...

 

RAD

8...7

4...3

2...1

6...5

10.9

 

Tighten bolts to 20 ft lbs. using above pattern

re-tighten to 40 ft lbs using the above pattern

re-tighten to final 60 ft lbs..... done.

 

 

After several full warms up and complete cool downs, or in a week or so when motor is cold re check the final torque is at 60 ft lbs.

 

The Z24 is well known for blowing head gaskets. The FSM recommends re-torquing the head bolts at every tune up or once a year minimum. On cold motor, loosen fully ONE AT A TIME and torque directly to 60 ft lbs. You can do in any order.

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Thanks for your help guys, I really appreciate it.

 

We looked at the Haynes manual today and found torque specifications as follows:

1. Tighten to 22ft lbs

2. Tighten to 58ft lbs

3. Loosen all bolts

4. Tighten to 22ft lbs

5. Tighten to 58ft lbs

We were a little perplexed at first, but this apparantly allows the head gasket to get a good seal.

 

Now onto another little mystery, we had a copper ring which came with our gasket set that we have no idea where it actually goes... it's about 5/8" in external diameter. (7/16 I.D) Does anybody have any idea what this little ring is and where it's supposed to go?

 

Thanks a bunch!

Harry

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The tightening sequence is much more important.  Next is the re-torque at every tune up to keep the head tightly against the gasket.

 

There is an oil feed hole from the block up into the head just above the oil pressure sender near edge. The gasket usually has a copper O ring in the gasket to seal this. Loose is... odd. It should look similar to this... 

Its the copper oval at top edge of gasket...motorL20Bgasket.jpg

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The gasket has an opening for the oil pressure hole, the copper washer wouldn't fit in that aperture in the gasket though...

It's a mystery...

 

Looking at the old head gasket it has the hole for the copper gasket you describe, but this copper ring is nothing like that.

Head-gasketoilpressurehole_zpsa53e5b94.j

MysteryCopperRing_zps6c37528d.jpg

(Dixon pencil added in for size comparison)

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Do you have a picture of the oil hole in the new gasket???

 

No, but the new gasket did have the copper ring inside that oil hole, this is just a mystery piece that we don't know where it is supposed to go.

 

Now if I've interpreted your post correctly, the tightening sequence is:

8, 7, 4, 3, 2, 1, 6, 5, 10, 9

 

(These numbers from the loosening sequence provided here)

 

Though I'm a bit confused because in the manual it has a tightening sequence 1-10, beginning from the center and then working out to the back and front like this...

TighteningSequence_zpse28f5b69.jpg

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Yes from the center outward. RAD is the front of the engine. 1 and 2 are in the middle. Tighten one then two, move forward to the next pair and tighten three and four, then five and six... and so on. 

 

RAD

8...7

4...3

2...1

6...5

10.9

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There are 10 bolts in 5 pairs.

 

1/ Tighten the middle pair

2/ Move to the next pair forward and tighten them.

3/ go back to the middle

4/ Move to the next pair to the rear and tighten them

5/ Move to the very front pair and tighten them.

6/ Move the the very back pair and tighten them

 

All bolts should now be at about 20 ft lbs plus or minus.

 

 

1/ Tighten the middle pair

2/ Move to the next pair forward and tighten them.

3/ go back to the middle

4/ Move to the next pair to the rear and tighten them

5/ Move to the very front pair and tighten them.

6/ Move the the very back pair and tighten them

 

All bolts should be at about 40 ft lbs.

 

 

1/ Tighten the middle pair

2/ Move to the next pair forward and tighten them.

3/ go back to the middle

4/ Move to the next pair to the rear and tighten them

5/ Move to the very front pair and tighten them.

6/ Move the the very back pair and tighten them

 

All bolts are tightened to 60 ft lbs... you are done.

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Right, so just to clarify it's me and my dad working on this truck.

 

We tightened all the bolts on the head cylinder and the valve rocker assembly to the specs listed in the haynes manual - but now we've hit a big roadblock. When we went to put the camshaft sprocket back on we noticed that we could not align the camshaft and the sprocket to TDC. We tried multiple things to get it on but the timing chain will not allow the sprocket to go any higher. As you can see in the attached pics, the camshaft is 1/4" to 1/2" too high.

IMG_0343_zps7a924603.jpg

 

IMG_0342_zps3b9e8f2a.jpg

 

It looks like we might have to take the whole front assembly apart. We took a peek with an oversized screwdriver and found that the chain guide is too tight, which means taking it apart to slacken it off. I had a local high school do repairs (ball joints and timing chain tensioner) which they don't seem to have done correctly now. So now I have to look for the box with a whole new timing chain assembly to see if the tensioner is still in the box - the bolts to the timing cover look as if they've never been removed.

 

Harry

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This is a common mistake and once you make it you will never do so again.

 

Before the cam sprocket is removed the tensioner must be prevented from pushing out. It is spring loaded... a very stiff spring. A wooden wedge is usually pushed down between the chain and the tensioner cannot push out of it's bore. 

 

Here's what you can't see down there behind the timing cover...

 

See that little shoe sticking out? Well it's spring loaded and keeps tension on the timing chain.

LooseChaintightened002.jpg

 

If the cam sprocket is removed the tensioner will pop out and it ends up like this...

tensionerout-1.jpg

 

Unfortunately, there is no way to get it back in unless you remove the crank pulley, the oil pump and drive spindle, water pump and the timing cover to get at it.

 

 

Next time you will be sure to get and use one of these...

tensionerblockoff.jpg

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Aye, we made a wedge out of a piece of wood we had and used that to hold the chain up while we took the cylinder head off. Unfortunately we couldn't get the wedge in before taking the sprocket off because the repair job by the high school obviously wasn't done correctly. Looking at the guide it is far too tight, so as you've mentioned this coupled with the tensioning spring coming out now means we have to take that all apart. Oh well, might be a mixed blessing really, since I do have a new timing chain we can also put on while all of that is off.

 

In fairness - the manual doesn't state ANYTHING about the wedge actually serving to keep the tensioner in place, just to keep the chain from falling into the sump.

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Like I said you'll never do this wrong again.

 

The wedge has to be pounded down between the chain to lock it in place before the sprocket is removed. It also helps to loosen the sprocket bolt first so it doesn't 'bump' the chain and dislodge the wedge. Also put transmission in neutral and block the tires. Now when you jostle the vehicle the wheels don't try to turn the motor and dislodge the wedge.

 

The blue one in the picture is not pounded in but goes all the way down and just blocks the tensioner.

 

 

 

As mentioned the water pump has to come off, oil pump and the internal spindle that drives it, and the crank pulley. Loosen the oil pan bolts around the front and half way down the sides so the pan can drop just enough to slip the timing cover out and back in. Hopefully the gasket is not torn.

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Welp we'll give all of that a go tomorrow.

 

In the meantime, let me introduce myself a little more. The truck's name is "Red Thunder". I've driven her for three years, failed my 'N' test three times and passed the fourth time with it. XD

I've driven her to Seattle and Portland twice, and also went to Kelowna in high-summer with some friends. I've primarily found her very useful for taking a family member or two out to Victoria or Nanaimo. I have a very-highly attuned interest in mass transit, so this shot should come as no surprise:

9346525915_c47f4c4638_z.jpg

(Full size here)

 

Since this shot was taken I have scrubbed off most of the rust off the chrome bumper and had the radiator replaced. Sadly that radiator replacement was obviously too late to save the head gasket.

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Does anybody know where I can download a decent online manual for the Z24 engine? I'm not so sure about going by the Haynes book again, just in case there's something else it isn't telling me - this was one prime example. It didn't mention anything about the tensioner, just keeping the chain from falling into the sump and off the bottom sprocket.

 

Harry

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The FSM doesn't mention it either because when assembling the motor you don't need it. The manual does not cover a head gasket replacement, but the tear down and rebuilding of the complete engine. It's just something you need to know.

 

26mm? socket for the crank pulley bolt and a long Johnson bar. Some have had good success setting the bar against the frame and bumping the starter to loosen the bolt. Or place in 4th with the hand brake on and kick the breaker bar to the driver's side suddenly. The pulley will come off by gently tapping it from behind with the socket. The timing cover should slid forward and off two small dowels.

Have a care as the end of the crank has a key way fitted with woodruf keys. On the very end is an small 'washer' called an oil slinger.... keep track which way it come off.

Now you should be able to get at the guides to replace them

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So we've gone ahead and removed the splash guard, fan and water pump behind it (antifreeze everywhere as a result D:)

 

Unfortunately two of the water pump bolts broke off inside the block. We're also running into special tools problems - where we don't have a 26mm socket - though we do have a breaker bar of sufficient length.

 

Is it a big problem removing broken bolts from the block? Does the engine need to be removed or can it be done in situ?

Has anybody else had this problem and overcome it without totally stripping it all down?

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Next time you will be sure to get and use one of these...

tensionerblockoff.jpg

 

hmmmmm, i feel like ive seen this before........ 

 

 

 

 

 

heres a link to but the wedge

http://www.amazon.com/Alltrade-648831-Nissan-Timing-Holding/dp/B0002Q8TV4/ref=sr_1_1?ie=UTF8&qid=1387400752&sr=8-1&keywords=nissan+timing+chain+wedge

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