Forum newb and his 34K original miles '80 Datsun 720 4x4

[Gradyfest]

Duuude I lost this thread, we haven't had winter show up yet and can still go get you those parts from the wrecker by me if you are interested.

 

I am, to include the transfer case knob as well.

[Gradyfest]

I knew that Mike, must of been in a hurry that day.

 

 

I recently purchased a 1985 2WD F250 with a 6.9 International Harvester diesel in it that has become my daily driver. It's a 30 year old truck but with that engine at 114K and a C6 tranny it is the most reliable and comfortable vehicle I have. It has power everything with A/C and cruise. None of which the 720 has.

 

I love driving the Datsun and it gets 100 smiles per gallon easily. But after I fix this coolant burning issue, I'm pretty sure I'm gonna retire it and put it in storage until further notice. The poor Datsun just sits in the sun everyday and with me having a more comfortable daily ride now, it just seems like the right thing to do. Plus since I've fixed all the exhaust leaks I can hear the bad bearing in the tranny better than ever reminding me I'll have that giant job soon if I keep driving it.

 

 

I just recently hit 48K and it looks like I'll be putting it away before 50K which is fun to say. Bought it a year and a half ago with 34K, enjoyed every mile.

[Draker]

I'll test it all later this week and probably just order a head gasket from Nissan tomorrow to have it just in case. I'm thinking and leaning towards it being the head gasket. I'll have to research more on here, but I remember I'll need a wood block for my timing chain of it goes that route. Do they pre-make anything that will work hassle free? Or is making my own out of wood it?

 

http://www.amazon.com/Alltrade-648831-Nissan-Timing-Holding/dp/B0002Q8TV4/ref=sr_1_1?ie=UTF8&qid=1447308814&sr=8-1&keywords=nissan+timing+chain+tool

[Gradyfest]

Kool, I ordered the chain tool off Amazon and a OEM head gasket (11044-U0804.) Shoud have everything I need by early next week. That's all I need right?

 

Will be pouring over the info on here about the job until then. I likes datzenmikes approach of taking the head off with the manifolds attached. I just did that gasket replacement and those lower bolts, even with a 1/4 drive 12mm swivel socket suck balls.

 

Can I just reuse the head bolts? I contemplated ordering them when on the phone with Nissan.

[84720FourWheel]

They aren't torque to yield, so you should be able to as long as there isn't any obvious damage to the bolt.

[Gradyfest]

Very kool man.

 

At first I was all stressin' the job. But it seems pretty straight forward and compared to my other vehicles, definitely the easiest one for a head gasket replacement.

 

 

What's good for cleaning off the old gasket once I get the head separated?

[Draker]

Very kool man.

 

At first I was all stressin' the job. But it seems pretty straight forward and compared to my other vehicles, definitely the easiest one for a head gasket replacement.

 

 

What's good for cleaning off the old gasket once I get the head separated?

 

 

Use this.. you'll be done in 5 minutes:

 

[Draker]

It's a yellow 3m roloc disc. DO NOT USE ANY OTHER COLOR.

 

Attach it to air, and go to work.

 

 

 

If you don't have air.. then razor blades will be your friend.

 

To give you some point of reference.. When we went to Shasta this august and Earl blew a head gasket, it was torn down swapped and running again within 2-3 hours.

[Gradyfest]

I don't have air but could maybe get it mounted on my angle grinder? That's the only thing I have that spins that fast.

 

I'm so stoked this is a easy job and I can get her on the road again!

 

My 6.9 International isn't quite ready for daily road work yet and I need the 720 for another month or so as a daily. My daily now is a 7.5L boss of a truck that is honestly my favorite truck but gets about 8-9mpg. Compared to 22-23 average with the little L20B.

 

I'm burning $$$ to fast right now!

[Draker]

You'll be able to knock it out pretty easy. Just block that chain with the tool... otherwise it will take much longer.

[mattyhacks71]

It's a yellow 3m roloc disc. DO NOT USE ANY OTHER COLOR.

 

Attach it to air, and go to work.

 

I used green, worked fine just don't grind forever. To make it easy get some gasket remover and spray it on where cack was left behind then take the wheel to it.

[Draker]

Green is too abrasive for aluminum, of course if your careful it could work.. but I wouldn't recommend it. 

[Draker]

Green is 50 grit, yellow is 80, white is 120.

[Busta Nut]

Good old fashioned scrapers.......

 

 

 

 

....I refuse to use air on my Datsun....for ANYTHING......

.....as soft as those may be....I feel it's still too much.....

 

It removes metal no matter how ginger you are.....and that upsets me becuz then you get uneven surfaces.....

.....head gasket.....critical area.....

 

Just my.....

 

[Busta Nut]

...and don't buy cheap ones.....

 

Cheap ones are made from cheap metals and will get fucked up way easy.....

 

I've had my Snap-On one for 15 years.....it's never seen the grinder.....

[Draker]

Ironically those are like 10 times the cost of a roloc disc. :)

 

If you chose the wrong color... you'll be fucked. Chose wisely.

[Gradyfest]

Well all my stuff comes in this afternoon to do a head gasket replacement. But before I start tearing it down I wanted to do a cylinder compression test to be sure. Well...

 

It passed! The number four cylinder held pressure like all the rest and was actually the second highest. I even popped off the radiator cap while it was pressurized to be sure. No change.

 

Cold cylinder pressure test results:

 

1- 149

2- 150

3- 159

4- 152

 

 

So...

 

 

It has to be the intake manifold coolant jacket then right? Bad gasket spot.

 

 

I replaced the #4 spark plug when I seen it was bad with a spare. I only ran the truck 1min to move it in the sun to work. Then when I took off the replacement for the cylinder test it was very wet again. I'm also loosing coolant very fast in the rad.

[Draker]

No. Just because the compression is good, doesn't mean you don't have a leak. 

 

Go get a block test kit (or rent from a parts house), and test the coolant system for hydrocarbons. 

 

 

[mattyhacks71]

Pull the head off, its not difficult. Get it checked and decked. Get a head gasket kit (comes with all the top end stuff, 50 bucks). Couple hundred dollars and a weekend, get er done!

[Gradyfest]

No. Just because the compression is good, doesn't mean you don't have a leak.

 

Go get a block test kit (or rent from a parts house), and test the coolant system for hydrocarbons.

 

Dang it. Returned the cylinder tester to Oreilly's and they don't rent such a kit. Closest Napa is a forty minute drive.

 

 

 

Pull the head off, its not difficult. Get it checked and decked. Get a head gasket kit (comes with all the top end stuff, 50 bucks). Couple hundred dollars and a weekend, get er done!

 

I don't want to replace a good working head gasket just because (if it turns out to be fine.) I plan on leaving the manifolds on and if it was the wet intake spot and not the head gasket, I'm right back to where I was when done.

 

 

I guess I need to find and rent, or buy this hydrocarbon tester as a next move...

 

 

I do have everything I need in case it is the head gasket now however. In addition I also have a spare manifold gasket if need be.

[Draker]

It's more likely to be the head gasket, but you're correct. Why pull it without doing the proper diagnostics first. You could just buy the kit online and have it shipped.

 

The block tester is not a sure fire test.. but I think in this case, you'd see what you needed to see to make a decision.

[Gradyfest]

I just topped off the coolant, it was almost a gallon low. I got out as much air as I could by squeezing the top hose to get the system as full as possible.

 

I then ran in it with the radiator cap off to look for bubbles.

 

I let it warm up past the thermostat opening and then some watching and topping off the entire time.

 

 

In big spurts, not a constant stream, I did see bubbles come to the top. The were all pretty big gulp like bubbles that came as fast as 4 seconds, and as long but no more than 14 seconds apart. I guess they all averaged around 8 seconds apart. I ran it until it was getting uncomfortable to have my hand on the radiator and this was consistent.

 

 

Now that leads more towards the head gasket right?

 

I can't think of how bubbles would come from it sucking coolant into the intake runner...

 

I'm trying to think of other ways to diagnose without buying the kit and spending more $$$

[mattyhacks71]

Why pull it without doing the proper diagnostics first.

 

Because re-re head gasket is a 3 hour job, could have been done and driving by now. And if its not? Well you have a fresh head gasket to not worry about for a long time.

Its either that or the intake/exhaust manifold gasket.

 

You can't properly diagnose until you physically look at the gasket and the head removed.

[Draker]

 

You can't properly diagnose until you physically look at the gasket and the head removed.

 

Not true. But without spending anymore money, it's probably the best way.

 

Get the engine up to TDC on the compression stroke.. pop that head off. Let see what that gasket looks like!

 

You'll have it off in no time!

 

When you remove the bolts from the head, be sure to remove them in just as you would when installing them. Go in stages and work your way around the head a little at a time, circle back, do it again, until it's off.

[wayno]

If number 4 cylinder spark plug is wet every time you pull the plug, it's time to pull it apart.

I would start with the intake/exhaust and check the gaskets carefully, if everything looks good, then pull the head, if the intake gasket has an issue around the water port, it will generally not stick to the metal in the effected area, it will come off clean, the W58 head does have water jacket holes in the intake manifold as far as I know.

When pulling the head, note how hard it is to loosen each head bolt, pay particular attention to the rear head bolts, are the back two easier to loosen?

Keep in mind that that every two revolutions of the crank a piston compresses air and sucks air out, when it compresses air it can force air into the water jacket, when it sucks air out, it can pull water out of the water jacket, now I will admit that your compression numbers don't point to any particular cylinder, but you have already said that #4 has been wet, there are two water jacket holes next to each other at the rear of the head, one is quite large.

I had an issue with air pressurizing my water jacket/loosing water, it was because my head bolt next to the thermostat went bad(pulled the threads out of the block), and when I took the head off, that head bolt was loose.

I put a helicoil into the block and I used an ARP stud kit to tighten the head down, have not had an issue since. 

 

 

Gradyfest, on 16 Nov 2015 - 5:58 PM, said:

I just topped off the coolant, it was almost a gallon low. I got out as much air as I could by squeezing the top hose to get the system as full as possible.

I then ran in it with the radiator cap off to look for bubbles.

I let it warm up past the thermostat opening and then some watching and topping off the entire time.


In big spurts, not a constant stream, I did see bubbles come to the top. The were all pretty big gulp like bubbles that came as fast as 4 seconds, and as long but no more than 14 seconds apart. I guess they all averaged around 8 seconds apart. I ran it until it was getting uncomfortable to have my hand on the radiator and this was consistent.


Now that leads more towards the head gasket right?

I can't think of how bubbles would come from it sucking coolant into the intake runner...

I'm trying to think of other ways to diagnose without buying the kit and spending more $$$