kats

After asking some of my friends about this , I tend to think there was a simple sealing type cap which was is used for the Z432 . I said 21430-E4201 was the only part number for the Z432 radiator cap from the beginning to the end , but this may not be correct reviewing the Nov 1969 Fairlady parts catalog ( 1st issued ) . The catalog listed only Assy Radiator, not mentioned about the radiator cap which is used on the radiator. This indicates we might have chance to have a certain part number for the cap . Just they did not show it in the first catalog . 2nd issued parts catalog is dated 03/1970 , as it is said later , the cap for the reservoir tank was replaced new one ( plastic) from Jan 1970 . We see 21430-E4201 for the first time in this 2nd issued catalog , also it is still listing 21430-E4200 ( cap push , reservoir ) , without mentioning a new plastic cap (21516-C0500) . but ironically at the production line , workers put plastic cap for the reservoir tank when this catalog was issued . So , I think there would be a simple sealing type cap there , maybe sharing with other models , and we know , parts catalog is not always correct and updated . I found a cap at the Rallye Datsun Roadster, I think this might be the one “ simple sealing type cap “ , as not showing “ A9 “ on the right hand side like a pressure relief type cap . And at the center part , the round rivet is different from the pressure relief type cap . Kats

You are right, the tank must have a little opening for helping suction, that is a check valve for the metal cap , and a tiny hole for the plastic cap . I drove my Z432 today , and i checked the reservoir tank , I see the coolant level raised about one inch before the driving. Engine operated normally, no hard driving, I now have a STD about the coolant level . Seeing my Z432 , two pressure relief type caps are working without any problem . I thank you all for the useful inputs here , I am learning and I need to amend some of my comments. So now , Why my Blue 240Z’s reservoir tank has air in the tube ? Looks like the coolant does not flow back to the radiator . The radiator cap is a new , and is a pressure relief type .It must be operational for both ways , let the coolant go out , and back in . Becaues of the radiator is not fully filled? Or there might be some cracks in the tube ? I need to check, it is interesting ! Kats

Thanks w3wikes, no need be pressurized, but need to be sealed at the reservoir tank ? Kats

Manuals , Fairlady Z manual for Japanese customers, and I have a very rare Fairlady Z manual written in English . Kats

Thanks Captain ! I did not know there is a check valve , so , even in my set up ( two pressure relief caps ) , coolant can flow back to the radiator as long as the reservoir tank is pressurized. I want to hear depressurized sound on the reservoir tank, but every time I pushed the botton, nothing happened . I wonder my Z432's reservoir tank is operating correct or not . The Fairlady Z manual says " looking at the reservoir tank from outside , to see if the coolant level is sufficient, half of the tank " this instruction is the same for the early type and later plastic cap type . I think we are on the same page there. But for Kats' installation on his blue HLS30U, he is using the later type reservoir bottle and that means an unpressurised bottle, one-way system. It looks to me as though Kats is getting quite a lot of coolant in the reservoir bottle. More than I would have expected. Japan has been pretty hot (to say the least!) lately, so maybe the cooling system is struggling to keep up? Kats, is the pressure rating on your 240Z's radiator cap quite low? Thanks Haha Confused Sad Alan , I just poured too much into the reservoir tank, I tried to let the coolant flowed back into the radiator using gravity ! But yes , my blue L24 is struggling in the high temp , I saw coolant level became higher than that of before driving. Kats

Thanks Alan , it is a nice picture ! Back to this picture, what would have been like if there are two pressure relief type caps , on the radiator and the reservoir tank ? Now my Z432 is just like that , two pressure relief type caps. In my Z432 , can the coolant retun to the radiator when the coolant cooled down ? I have never driven my Z432 so hard , then I really do not know what would happen when the radiator overflowing. And my guess is , there would have been a pressure relief type cap only , would not have been a simple sealing cap. Because 21430-E4201 is the only part number for Z432/432R , and this is the pressure relief type cap . Kats

To begin with , Nissan Cedric, the coolant system . This is what we want to see , this picture explains exactly what the coolant moves between the reservoir tank and the radiator. We see the allows at the tube vice versa , and the radiator cap looks non pressure type , and the reservoir tank cap looks pressure type. This is excerpted from the L20A and L24 Nov 1969 manual . Also pictures from an owner’s manual of Nov 1969 Nissan Cedric. More to come . Kats

If my guess is true, the early set up on the reservoir tank ( push botton cap ) is useless. It becaomes "over flow catch tank " like Alan said. I need to see other early Z432s as much as possible to clear my question. Kats

For the early "a metal cap with a push botton" type reservoir tank, What I am confused is, seeing the manual , to my understanding, the manual is saying "pressure relief valve is on the reservoir tank , not on the radiator " . OK, However, I can not see any specific part number for the radiator cap which should be put on the radiator. I mean , in this set up, the radiator cap must be a simple "non pressure regulator " type. BUT , ,, We only have a single part number for the Z432 radiator cap , from the beginning to the end, that is 21430-E4201 , this is the biggest question to me. From Jan 1970 , simple plastic cap (21516-C0500) began to be applied on the reservoir tank, if the manual is correct, this means the radiator cap must be replaced by pressure regulator type, to achieve keeping good coolant temp in the water cooling system. But there is no new part number for the radiator cap when this new cap was applied. We only have a single part number for the cap on the Z432, "21430-E4201" , so , I guess Z432 is different from the manual in terms of radiator cap set up ...I will hold of my conclusion until I see the "non pressure regulator " type cap on the Z432 radiator. I will upload some pictures. Kats

Let me explain , I learned and confused, and found something may not correct on my Z432 ! Thanks Alan, Patcon, gnosez. Kats

Thanks Alan ! I learned , Overflow catcher , yes that is suitable for the bottle. So I think If I want dual path of the coolant, I should place the bottle as high as the radiator neck . I should make a bracket near the front shock tower . But I don’t think I would do it for my car . Kats

Once water cooled down, the tube has air in it . I found it . Why does the car have the bottle for ? I thought to keep the water in certain level . Any input appreciated . Kats

Hi , I installed the bottle into my blue 240Z , one small issue made a single bolt useless, the bracket of the upper radiator is interfering a little bit to the hole for the bottle bracket . I need to either cut or bent the interfering portion , but I don’t want to do it . Just let the hole vacant this time , I tightened only one lower bolt for the bottle bracket. I took for a ride and I don’t see any problem so far . Z432 has different bracket for the radiator, it is already concerned for the bottle. During this operation, I did not want any air bubbles in the tube from the radiator filler neck , I tossed the bottle higher than the neck , then water from the bottle goes into the tube all the way to the filler neck . Then I opened the cap little bit to let the water overflowing from the neck , then tighten the cap , now there are no air bubbles between the radiator and the bottle. Am I right for doing this ? Kats

Yes ,it is super ! So , I am thinking something.... Kats

Hi Alan , you have an early one, that is wonderful and very clean , your yellow is no need to do something, I like it . Yes there are holes for the bracket , that is why I want to try . And I want people to know the bottle is useful for everyone. Not original for L series engined car , but this modification is easy to resume normal so purists can take this “ just a while “ . Kats

Gavin. I made you confused, sorry. I am trying to install the bottle into my Blue 240Z . The first picture is the one which I recently bought , and This is going to be on the 240Z . The bottle is STD equipment for the Z432 and Z432-R . And not applicable for any other S30 models. Nor available as an optional item. I too think why only Z432 ? Why not on 240Z ? This bottle was shared with Cedric/ Gloria at that time , they have different brackets though . Kats

Thank you 7tooZ and 240znz , I wish Mr .Tamura could tell more about our cars. Kats 7tooZ , I will send some pictures of the fog.

My Z432 , when the restoration was in progress , the car did not have a metal neck. Lost at some point for sure . And an original bottle was very yellowish. So a new 3rd type bottle and an original bracket were joined as one. Later I found a metal filler neck and , the metal cap is still available at local Nissan dealer today. Kats

Thanks Patcon & Gavin , I saw the thread , they are really useful information , amazing work ! The bottle is very thick in its wall , I assume it gives a lot margin to avoid crack/ deterioration . Here are the depth of differences of the bottle by date.

Hi , here in Japan everyday so hot , I am worried about my cars can be melted down . Today I am going to show this , a reservoir tank for Z432 . I think it is also good for other models , especially in height temp operating during in Summer . I will report when I install it . Can I make it more white like new ? Kats

Hi and thank you everyone here, this is an old thread. I suddenly wanted to put this picture. What do you see in this picture ? I see a beautiful female face . She has got beautiful eyes and nose and lips . Many people were involved in developing of this car , but Mr Tamura did a great job . Who was there always in his mind when doing this beautiful work . Kats

Hi Captain !! You are the best engineer for helping others , I wish I can do it for my cars like that . Kats

So, if you have the electical fuel pump near the differential gear on L series engined car like Nissan manual said about Z432 fuel system, it will help for preventing percolation , but I think it will not make a big difference. Like everybody here think SU carbs on the exhaust is the problem. I think Nissan manual should ammend saying like this , " Z432 has carburators opposite side of the exhaust headers. This prevents vapor locking / percolation " , not come from fuel pump location . However our cars are no ploblem under 90 F with a stock fuel configuration as long as cars are cruising . Kats

Thank you everyone, I am learning, should not be confused about percolation and vapor lock . I am a student here ! Kats

The Fairlady Z manual says , Z432 has a fuel pump ( electrical ) which is located under the floor near the diff . This prevents vapor locking . The reason why Z432 does not have a fuel return system is , no need to concern vapor locking . I did not know that , is this true ? Kats