1978 Datsun 620 - "Sendy"

[banzai510(hainz)]

guy didn't change the antifreeze enough.

 

yeah just break the bolts loose then put on TDC and take apart. But if just take apart to take apart it don't matter

[datzenmike]

9 hours ago, bxadook said:

I am sorry hainz but curiosity got the best of me, and I think I ended up making the right choice. In the donor motor I found: 

 

 

https://photos.app.goo.gl/bhWbyR5PhYoJGQKR7

 

Video of sludge coming from water pump. I sent this to my brother via text if you are wondering about the speech. 

 

 

 

Pitting in the water pump? Sorry I cleaned up the sludge when I took this photo.

 

 

Latte coolant / oil coming up through the valves? 

 

 

It had a square port manifold gasket, yet where the exhaust flows it is round. Is this normal? My 1978 L20b did not look like this at all! Its almost like a portion of the head was eaten away by acidic exhaust? Every exhaust port looks similar. 

 

https://photos.app.goo.gl/FECdEJJwobVE9Ba68

 

The exhaust ports are all shit. The intakes actually have a portion at the 6 o'clock position(gravity dependent I guess) where it is eaten away. Is the EGR bad? Is it recirculating too much acidic crank case gas? Was it the coolant leak into the oil worsening the pH of the motor?

 

 

 The gasket in question. 

 

 

This is the intake manifold. My 1978 motor was clean - you could see the manifold metal. Here is the 1980 motor coated in a black tar. The coolant ports on the head for the intake manifold also appeared to be clogged. Half of one of the intake ports on the manifold was completely blocked off with crap. 

 

I am pulling the head off tomorrow. Will make sure to set the motor to TDC before I do so.  Super curious as to what I am going to find, I suspect there will be a blown head gasket. This is so cool, learning a lot. 

 

All I wanted is the transmission. I hope it is in good shape. Have new seals coming in this weekend, and clutch coming in next week. If the block ends up being crap I will turn it into a table or something. This head appears to be totally ruined. 

 

 

 

 

 

This is from not running anti-freeze coolant mix. Could be the rad leaked and the owner just kept adding water. Just laziness.

 

 

 

Again adding tap water with dissolved minerals (hard water) water boils off leaving scale. Soak in CLR and it will dissolve the scale. Always top up with distilled water.

 

 

Brownish tint is not changing the oil enough. Don't use today's motor oil. Use diesel oil like Shell Rotella T4. It's not only high in ZDDP but high in detergent and will clean that off as you drive.

 

 

 

Normal other than running too rich and carboned up. Maybe short trips with the choke mostly on all the time or choke stuck on.

 

 

Again running too rich. Fumes from the PCV added to this. Was there a cloud of smoke behind you?

 

 

 

Worst filter ever made and to me looks like printing on outside is from years and years ago. Don't ever use fram.

[bxadook]

Yep mike! This is just a 1980 L20b motor I picked up that  came with a 5 speed transmission. I did not take care of this motor, I have only had it for a few days. Actually felt how this motor pulled before it was removed from the truck it came from and it actually felt stronger than my 1978 motor! This got me super excited as it felt like it was a win-win. Now I am just a little bit bummed.   I will see what I can do to clean everything up, and dissect the head and block today. 

Edited June 13, 2020 by bxadook

[datzenmike]

I know that, this is the previous owner.

 

Yours may not be running as it should and I've found that when you aren't holding on to your steering wheel a car seems to pull stronger when someone else drives it.

[banzai510(hainz)]

The anti freeze thing I also was the guy who just used hose water to fill the rad tank being cheap is one of the issues.

 

hope you see what’s good on the motor and maybe get the block cleaned and maybe your fine.just check the front cover  if your going to reuse it.

[]2eDeYe]

Definitely look the block over. Good L20 blocks are getting harder to find.

 

Check for cracks between the head bolts and the 2 & 3 piston.

 

 

[EDM620]

On 12/13/2019 at 8:35 PM, datzenmike said:

Engine oil. For this you really should do some research on the ZDDP controversy. ZDDP is a zinc anti scuff additive added to the oil but in the last decades oil makers have been dropping the levels from 1,200 PPM to as low as 600PPM for two reasons. Most engines today use roller cams and don't need the protection and it's harmful for today's catalytic converters so they are slowly fazing it out. Our Datsuns are 40 plus years in the past and were designed to use oils high in ZDDP. Primarily to protect from cam to tappet or cam to rocker scuffing. Oil companies have said that today's oils are reverse compatible and that the levels in the past were too high to begin with so lowering them does no harm

 

Another source for oil that's high in ZDDP is "HD" or "BMW" motorcycles - BMW boxers are oil cooled and the ZDDP is pretty critical, HD oil is just slightly less expensive but easier to find...

[datzenmike]

Chevron Delo 400 is another and pretty much anything marked 'Racing'. Ask for a 'flat tapped' oil and the counterman should be able to supply what you want. Today's push rod engines have roller cams that by design don't 'rub' metal on metal. The higher levels of ZDDP aren't needed and it messes up the latest catalytic converters. You can buy ZDDP and add it but screw that, just use an oil that is correct.

 

Will your precious L series OHC valve train survive another 80K on the oil made with less than half the ZDDP. The oil makers say so but I'm not taking that chance.