Jump to content

Another new 620 owner


Recommended Posts

This should of been my first post but better late than never. Need tips and advice how to keep this beautiful gem I stumbled upon running and up to date. Opened minded to anything to keep her legacy going. Found her in Beverly Hills mansion in a flooded basement so she needs some love. Thanks.

Link to comment
  • Replies 24
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

This should of been my first post but better late than never. Need tips and advice how to keep this beautiful gem I stumbled upon running and up to date. Opened minded to anything to keep her legacy going. Found her in Beverly Hills mansion in a flooded basement so she needs some love. Thanks.

How flooded? You will need to drain and replace all the fluids if it was submerged, it would be good to replace the coolant and thermostat also for the little overheating problem,and go from there

Link to comment

Do you think the overheating might have to do with the little electrical fan not pulling enough air through the radiator? Did you install that?


If not you need to ask yourself why the PO pulled the water pump fan and installed the electric fan. Likely the fan clutch is dead. Likely the whole water pump needs replaced and reinstall the factory fan blade. IMO

Link to comment

That's your problem right there. Fan clutch is dead. Can't pull heat out of radiator. Same thing happen to my truck last summer.


Prolly electric fans too small to get the job done. Drain coolant, save to reuse cause it's new, and swap/replace your water pump. It's easiest to remove the radiator when doing this. Also install your factory fan before you reinstall the radiator. It will work great.


You could also take your radiator to a radiator shop, if they still have those in LA, and have the radiator flushed before reinstalling just to know it's been done.

Link to comment

Update: So I took the water pump off and it was a bit rusty, gasket torn, and worn out. I cleaned above and around the wholes took off all the gunk and build up around them I noticed a crack on one them. This could've been the reason it was over heating? I have no idea but please do give me some feedback on what to do or what you think.



Link to comment

Personally I was gonna say the same... you have an l20b right. isn't there another bolt right below where it's cracked that should hold things tight.. if it was an l16 I'd be concerned because there's only one bolt in that corner could develope a leak. In your case I wouldn't bother untill you have to.. that Crack should have nothing to do with overheating, but the back of the water pump looked questionable.. did you flush the system at all? Better fans will help too....

Link to comment

 Clean it very well and JB weld it as the others or a Black RTV such a Permatix oil resisitant stuff.

Tighten bolt to like 7 pounds I think it is and find a spare front cover when you can.



most fan clutches stop working by locking up. so it turns in to a old style fan that always work. So is it locked up or not??????? If locked up that's not going to cause a overheating proplem.


once you get up to speed the fan isn't mush good anyway. so if its a cold day then your over heating is not fan related.


Is your lower hose collaspeing when you give it gas? if yes they might be part of the proplem.


Are you using water? if yes ck the spark plug maybe your sucking water up. Sign is a very clean spark plug.  Maybe its going into the coolant system?



So it would be getting hot even with no thermostat in there if head gasket bad


Have you tried a 160 temp stat?   But this is a hail mary on my part.

Link to comment

That is an aftermarket AC unit that hangs under the dash, even if it might have Datsun printed on the switch plate.  And the AC drier is an aftermarket utilizing slide-on hose fittings with hose clamps. The compressor bracket looks to have been removed and the stock fuel pump reinstalled. Looking at the damage in the pics it is probably due to a loose York compressor bracket,  or an over zealous PO using the wrong bolts or over-tightening. I can't tell you how many broken front covers and burned up L motors I saw back in the day due to individuals and "specialists" adding after market AC's. They were accustomed to bolting on those big vibration piston York compressors onto American made steel V-8 motors that could handle it. When they started slamming those units onto the L motors they broke stuff all the time. It is sad the latest AC technology combined with their ignorance with import cars, made them specialists at killing the reliable little Datsun motors.  


I agree with Banzai. 1)  First find another front cover and replace the broken one. Put a WTB ad, I would think someone will help you source a reasonably price one.  Protect the motor from bleeding oil and further damage from vibration and unsecured bolts.


2) Remove the AC condenser if it is still there blocking the flow of air thru the radiator. Free! (couldn't see if it is still there in the pics or not.) Flush and back flush the motor. DZM has numerous posts about how easy it is, and free, or just a thermostat gasket.


3) Put in a reliable stock NEW clutch fan from Rock Auto, they're cheap. Rock Auto has a Gates or AC Delco for $35-45 + shipping. This is a no brainer for reliable cooling. Get the thing running well before "tricking it out."  I can't tell you how many guys with heating problems I see at meets, only spin their fan to see they have a worn out clutch fan. I mention it to them... they want a quite 4 blade fan instead while they get stuck in So Cal traffic, only to have more heating problems. I laugh my ass off.


4) Find a stock 7 blade 620 fans, they're still pretty common and easy to find and reasonably . Another WTB ad should solve that.


5) Find yourself a fan shroud. If it had AC back in the day it looks like someone took it off and didn't put it back on. Add coolant and you have a no problem, no-worry cooling system as long as your hoses, freeze plugs, and head gasket are still ok.  


Back in the 70's I drove all over the desert communities in Riverside, San Bedoo, and Palm Desert with this setup and never had cooling issues.  Or you could try an aftermarket electric fan setup. I like the concept for being quieter. I just have yet to see a setup that looks like it will pull as much air as a stock fan,  or installs as neatly as the stock set up.


I gave my AC advice to Noriega something on ratsun. He cut down a stock cast iron compressor bracket, bolted on a rotary compressor to it. He too was using a stock worn out clutch fan and had heating probs.. I sold him an 8 620 blade AC fan, and he bought a new clutch fan, can't wait to see it again on his chopped 620 at the ER swap meet in a couple weeks and see how its doing now.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.