1979 pickup 620 head gasket job info needed

[79rv620pickup]

Hi, I think my head gasket blew? getting water in crankcase and running hot.

 

I went to a shop around the corner and the guy refused the job saying when you do a gasket job you have to replace the timing chain cover? and when you loosen the timing chain? sometimes the parts come apart in pieces? Is this true? How did the timing chain get involved to do a head gasket? I'm no mechanic but might become one for this job since he said it might cost 13 to 1600.00 to change a head gasket? Does any of this sound logical to anyone ?

Thanks for any help anyone can provide

Harry

[hessianben]

Mods: maybe this thread would be better responded to in the "ENGINE" category?

 

 

In regards to your problem, IF it is a headgasket, unless there is something else really wrong with the motor, that price is ridiculous!

However, he is correct that the timing chain does come off when you remove the head.

I recently did my own head gasket and timing assembly (with no previous experience) with help from everyone here.

This video from Hainz (Banzaii) was my step-by-step guide during the process.

http://www.guba.com/all/search?query=hainz&set=5&x=34&y=3

 

It's really not hard, and parts are inexpensive.

Do it yourself, and post your questions in the 'engine' topic section with lots of photos.

You're in the right place!

[slodat]

This can be done with the video mentioned above. I would pull the engine personally. It is much easier to work on an engine when it is on an engine stand... Just my .02.

[]2eDeYe]

You only need to replace the timing cover if it's cracked, worn or corroded.

 

Corrosion is the most common problem, it will be pitted in the waterpump area. This can lead to cavitation and overheating. I've only seen a couple bad covers.

[hang_510]

if you cant do it yourself, DO NOT go back to that shop.

 

the timing chain is attached to the cam/head(=OHC), so it has to be removed to pull the head off. it can be done w/o issue...

but if your like everyone else, the chain tensioner will fall out, requiring the cover to be removed and then reused (replace only if necessary)

 

making the simple task a real :cursing:

[datzenmike]

Your mechanic is a douche bag and is trying to take advantage of you. Do not go near him and bad mouth him to everyone you meet.

 

A good shop can do this job in 3-5 hours so $250-$300. I had a problem with my old L16 and had the head off a few times so the bolts were clean and new. I changed the head gasket in an hour and forty-five minutes once, but I had lots of practice. You should be able to buy most of the tools and a gasket for $100 and you get to keep the tools. You will need a 10mm Allen are wrench socket to remove the head bolts and borrow or rent a torque wrench for tightening them,... that's about it.

 

Here's a wright-up I did a few weeks ago

 

CHANGE HEAD GASKET ON L SERIES ENGINE

 

Drain coolant at least half way.

 

Separate exhaust to down pipe.

 

Set engine at TDC... important! GET IT RIGHT! Put transmission in neutral and block wheels also IMPORTANT, remove air filter, unhook throttle cable, any air pump hoses at air pump. (if equipped) vacuum line to brake booster, PCV hose at intake, idle cut and choke heater wires, vacuum line to distributor, top rad hose at head, vacuum line to charcoal canister, unplug spark plug wires at plugs and move out of way, unhook temperature gauge wire at thermostat housing, disconnect fuel line at pump inlet, remove battery ground cable, remove top heater hose from back of head, unhook water return hose from intake manifold where it joins the lower rad hose, remove valve cover, slip socket extension through cam sprocket to lock it and loosen cam sprocket nut... don't remove yet!, check you're still at TDC (and adjust) and drive wooden VEE wedge down between timing chain and chain guides to lock it in place. This will prevent the chain tensioner from falling out... if you don't know, find out or you will be doing twice the work to fix this mistake, mark the timing chain and cam sprocket so you can assemble in same relationship, remove cam sprocket, loosen and remove 10mm Allen head bolts starting with the front two, then the back two and alternating front and back and working toward the middle, keep track of where they go for reassembly, remove the two 10mm bolts at front of head that screw into the timing cover.

 

This should have the majority of things disconnected so that you can remove the head AND the intake and exhaust manifolds as a unit. Grasp the fuel pump and intake and rock from side to side and the head should easily break loose. Get help and lift the head with manifolds up and off. Avoid turning the carb upside down if possible to prevent stirring up sediment. If worried about this you can remove the carb before hand. Find the two alignment rings or dowels either in the head or block, clean and re-install when ready to assemble. Locate the blown area of the gasket and inspect it.

 

Tilt head just enough to wire brush or use an angle grinder with wire wheel. Use care, the aluminum is soft. Get it as smooth and clean as possible. If this had blown between cylinders or you had driven it high into the hot range with lots of steam I would say check the head for warps. Thoroughly clean the head bolt threads and wipe with an oily rag. Inspect the blown gasket area, there should be no indication of it on the clean surface.

 

Fill the middle two cylinders with rags to collect the dirt and wire wheel the block surface. Again, as clean as you possibly can. You can't over clean these two surfaces. Clean out head bolt holes thoroughly IMPORTANT! Inspect the blown gasket area, there should be no indication of it on the clean surface.

 

Install new gasket on block dowels. Lift head onto block and finger tighten the two rows of head bolts. Make sure that the cam has not been rotated while the head was off. The aligning dowel pin at the front should be at 12 o'clock and the first two lobes set at 10 and 2 o'clock.

 

Use a torque wrench and begin tightening in the middle and working outwards to front and back like below:

 

RAD

7...8 P

3...4 L

1...2 U

5...6 G

9..10 S

 

Use this sequence and tighten to 20 ft lbs. Start at the beginning and in the same sequence torque to 40 ft lbs. Finally in the same sequence torque to a final 60 ft lbs. A few lbs either way is not as important as the sequence that is used.

 

Match cam sprocket mark to timing chain mark and install onto cam alignment dowel, don't forget fuel pump eccentric. Tighten and remove wooden wedge. The rest is more or less the reverse of disassembly. After a dozen full warm ups and cool downs, check the head bolt torque with engine cold. You might want to warm engine and set the valve lash while the valve cover is off too.

 

I had the gasket blow on my '78 L20B for no reason I could see other than 300,000 km. It blew out water above the #3 spark plug but was also blowing steam out the exhaust. $23 for the gasket and $2 for gear clamps I didn't use. A very good, very cheap and easy fix.

__________________

[Phlebmaster]

Mods: maybe this thread would be better responded to in the "ENGINE" category?

 

 

In regards to your problem, IF it is a headgasket, unless there is something else really wrong with the motor, that price is ridiculous!

However, he is correct that the timing chain does come off when you remove the head.

I recently did my own head gasket and timing assembly (with no previous experience) with help from everyone here.

This video from Hainz (Banzaii) was my step-by-step guide during the process.

http://www.guba.com/all/search?query=hainz&set=5&x=34&y=3

 

It's really not hard, and parts are inexpensive.

Do it yourself, and post your questions in the 'engine' topic section with lots of photos.

You're in the right place!

 

Hainz's video is what I used to learn about what parts need to come off before I did my L16 for the first time. :D

 

It is very simple once you have done it once....watch the video and take notes. The most important thing after that is to take pictures of your motor before, during, and after so you have a reference point if you get stuck.

 

There are a few tricks with the timing chain...if you intend to just do the head gasket then you will need a simple 1" dowel about 10" long to place into the timing cover to prevent the chain tensioner from falling out. Been There!! :blink:

 

Here are the steps I follow:

 

1. make sure you set your E brake and shift your tranny into neutral, chock your tires.

 

2. pull hoses....(fuel line, vac lines, and coolant lines on the thermostat housing and the rear of the head) Drain the coolant first. :D

 

3. Pull wires....(Pull distributor cap leaving wires attached and disconnect from plugs, any wires connected to your carb, loosen your spark plugs) Then pull off your intake and exhaust manifolds with a 12mm socket. (make sure you have gaskets to replace the old ones)

 

4. Pull off your valve cover with a 10mm socket and line up your engine to TDC, making sure that the #1 and #2 cam lobes are at 10 & 2 and the "V" mark on the cam sprocket is lined up with timing mark on the # 1 cam tower.

 

5. NOW...shift your tranny back into gear once it is at TDC and use a 19mm socket to loosen the cam bolt. The tranny being in gear and the E brake will keep the motor from turning on you. (DO NOT TAKE THE CAM GEAR OFF YET)

 

6. Next you will need the 1" dowel...place it down the center of the chain untill it stops. It will be sitting on the chain oiler. This prevents the chain tensioner from coming out and making it so you don't have to remove the front cover.

 

7. NOW...remove the cam sprocket allowing the chain to rest on the dowel. ( Be careful....Do not allow the chain or crank pulley to move from TDC)

 

8. Next you will need a 1/2" 10mm allen head socket and a breaker bar.....carefully break loose all of the head bolts and remove. Do NOT remove the cam towers. The head should be able to break free with a little wiggle, pull strait up once it is loose. DO NOT set your head on anything with the valve side down.....lay on it's side so you don't bend your valves. One more thing...don't lose those head line-up/positioning thingys. They like to pull out of the block and stay in the head sometimes.

 

9. Clean your block and have your head examined :lol:

 

I hope this helps......:D

 

EDIT: I did not see that Mike had already posted a procedure....oh well, Can't let him have all the glory. lol

Edited February 9, 2009 by Phlebmaster
Dangit Mike lol

[Bleach]

Toyota front covers wear away. That is a common problem with the 20R and 22R. This is a Datsun. The front covers lasts for half a million miles.

 

I'll change the head gasket, oil pan gasket, and put in a whole new timing set for $900. Bring it on over :D