Blown head gasket?

[StewyN]

Hey guys,so i tore into my engine today under the assumption of a blow head gasket. (smoke rolled out of the radiator filler prior to tear down) got the head off and the head gasket doesnt seem to be blown, nor are there any cracks in the head. but cylinder 3 was plumb full of coolant. is there something im overlooking or would this be normal for a head gasket failure?

[datzenmike]

Sometimes very hard to tell. The head could be warped and lift off the gasket and coolant sneak in over or under it. 

 

Ah a 720 Z24 these are well known for blowing the head gaskets. The preventative is to re-torque the head bolts once a year. Too late now but good in the future.  I guess the heat cycling compresses the gasket or it de-laminates and the clamping pressure is less. Re-torquing just keep the head on tight. Here the head basically becomes 'loose' and water pushes in.

 

I would definitely check the head for warp before putting a new gasket on.

 

 

 

Here's another thing that is a little late, but,.... did you block the chain tensioner so it can't fall out before removing the cam sprocket???

 

 

[StewyN]

well i had attempted to but didnt do it well enough because my tensioner popped out. what is the warp allowance on theses motors?

[datzenmike]

Well the timing cover has to come off to reset everything in place. Don't forget the bolt behind the oil pump... which has to come off also.

 

Loosen but don't remove the crank pulley bolt.

Take everything off the front cover, I think you can leave the water pump on  but one of it's bolts goes through into the block so get it.

Remove the front and a couple down the side of the oil pan and the 4? coming down from the front of the head.

Be sure you are at TDC

Remove crank pulley by tapping on the back side with a large socket. Just keep tapping, I have never used a puller for the dozen or so that I have removed. Hopefully the crank keys stay in place.

Timing cover should slide forward and off two dowel pins. Pan gasket should be ok or slide a butter knife along to separate it.

 

Clean the two surfaces perfectly, have a care the timing cover is soft aluminum.

Now is a perfect time to replace that old crank seal.

Place the head and gasket on and put a couple of bolts in finger tight to hold in place. Be sure the 2 head alignment dowels are in place. This will allow the timing cover to slip back into place. Tighten head later.

The timing chain has two bright links that line up with the DOT on the crank and the cam sprockets (#2 hole) on the dtiver's side. While at the same time installing the chain tensioner.

Put together. Add a dab of RTV at the three way junction of the timing cover the block and the oil pan. Both sides. If applicable RTV the pan gasket both sides. SPARINGLY.

Same with the head. All it seals in is fumes and light oil spatter.

 

When finished torque head bolts and crank sprocket.

 

[paradime]

I don't know that there is a "warp allowance" figure on the head. You'd want to pay attention to the Max warpage though. According to the Z24 manual that's 0.2mm. 

[StewyN]

with most of the engine being pulled apart, whats a good way to brake the crank bolt loose? i dont really want to spin the engine backwards

[MaxChlan]

1 hour ago, StewyN said:

with most of the engine being pulled apart, whats a good way to brake the crank bolt loose? i dont really want to spin the engine backwards

I threw an old screwdriver in the camshaft sprocket to keep it from spinning, cracked the bolt loose and then removed the screwdriver. 

[StewyN]

yea i have the head pulled off of the engine right now. didnt really plan on letting the tentioner come loose and have to tear this far into it

[datzenmike]

Engine in truck? Put in 5th, set parking brake and have someone hold brake pedal down hard. Set the socket and breaker bar downward and take a couple of practice 'swings' then kick sideways with work boot on. Like stepping on ladder rung. Do it once, do it hard and it will let out a loud CRACK and it's done.

 

Oh yeah... lefty lucy.... righty tighty.

Counter clockwise

Kick towards the driver's side. ( ? these suck )

 

Ive loosened crank bolts with the engine laying on the ground. Hit hard and the inertia will hold the crank well enough.

[StewyN]

cool got that broke loose just as it got dark, back at it tomorrow after work i suppose. so another question, are the head bolts on these engines reusable? Ive heard mixed opinions on this across all makes and models of engines. some say always new, some say it doesn't mater as long as they look good.

[datzenmike]

Yes, totally reusable if undamaged. Be sure to clean the threads and the threads in the block thoroughly. Wipe them with an oily rag. Torque is this pattern...

 

R A D

8.....7

4.....3

2.....1

6.....5

10..9

... to 20 ft lbs.

Same pattern to 40 and finally same pattern to 60 ft lbs.

 

Once a year on a dead cold engine, loosen only one bolt at a time and torque directly to 60 ft lbs. Any order you like as long as only one bolt is loose at any one time.

[paradime]

I thought once the head bolts are fully torqued they stretch a bit and need to be replaced once removed. Is that just for more modern engines, or a line of BS so manufacturers can make more money? The Truth is you'll never get a straight answer to that question, so as a rule when ever I'm investing time and money on repairing a head I go the extra $ to ensure longevity.

 

It appears you experienced blow by on your head gasket and as Mike mentioned possibly from loose head bolts. Decking the head to ensure it's flat, and a set of ARP studs might set you back $250, but will go a long way in piece of mind. Not saying anyone's advice is wrong, just offering another perspective. 

Edited August 6, 2018 by paradime

[datzenmike]

TTY or torque to yield are supposed to be more accurate. They are tightened to a specific 'tightness' and then given an extra 1/4 turn which stretches them. The bolts are now like a rubber band and hold better with less effort. Once stretched they should be replaced. The L and Z (and before them) are just super thick and strong and never reach this 'plastic' zone when torquing. KAs use TTY head bolts

 

Myself...  it's just a way to use thinner bolts and lower the cost during manufacture.

[distributorguy]

I typically go an extra 5 lbs higher on a used head stud to accommodate for stretch.  Dangerous game.  

A torque to yield torque wrench will run you North of $600, but yes they are very accurate.  For example, my connecting rods are either 60 ft lbs or 25 ft lbs plus 65 degrees.  

Edited August 8, 2018 by distributorguy

[Charlie69]

I use one of these when there is no transmission installed.  Works great on all engines.  This is the only EMPI tool/part I recommend.

 

EMPI Flywheel Lock Tool