Cooling system pressure

[Comfort Eagle]

Hey guys,

 

 

I seem to have a small coolant leak now that I have buttoned up my SU's on the 510. I think I have found it,but I need to ask you guys few questions. The radiator cap I have does not list a system pressure,and neither does my owners manual. What should I set my system pressure tester at to locate a leak? I have it at 15psi for now,and so far it loses a couple of psi over an hour or so. Does this sound acceptable? I have been told in the past that air can leak in places coolant can't.

[sssr20det510]

Hey guys,

 

 

I seem to have a small coolant leak now that I have buttoned up my SU's on the 510. I think I have found it,but I need to ask you guys few questions. The radiator cap I have does not list a system pressure,and neither does my owners manual. What should I set my system pressure tester at to locate a leak? I have it at 15psi for now,and so far it loses a couple of psi over an hour or so. Does this sound acceptable? I have been told in the past that air can leak in places coolant can't.

 

when we are checking for coolant leaks i bump the pressure up to 25 psi let it sit for 15 min and if it dosent drop than your ok

[Comfort Eagle]

So I have still been battling this problem. I have had it pressured up to 15 psi all night,and it only dropped maybe 3-4 psi. However I have a wet spot or two under the car. They are large,but not puddles per say. Also I have some green coolant on the top tank of the radiator at the lip. It is near the top radiator hose,but that connection is tight as hell. Also I see one wet spot on the passengers side of the car under the engine,and also it is wet around the fitting in the back of the head near the rear most spark plug. I tightened that hose fitting,but it still seems to be wet around there. Should I worry about these leaks if the pressure tester drops that little over that amount of time?

 

 

Chris

[banzai510(hainz)]

look under the intake manifold (Look really good)ands see if the leak is from there. from the water passage area by the exhaust washers.

 

sometimes get motor hot then shut off and listen for bubbling

 

try another cap I think 13 pounds is the one you need and maybe try a different stat. try a 160 stat 54mm size generic one. might be cold in winter for you if using heater.

 

 

also the water pump has a samll hole on the bottom of it. this will leak slightley when the whater pump seals are strating to go bad.

[MikeRL411]

QUOTE also the water pump has a samll hole on the bottom of it. this will leak slightley when the whater pump seals are strating to go bad.

 

Nissan used to stock a water pump rebuild kit, hopefully it is still in the parts list. Worked like a charm [and for a change actually cost less than a new water pump].

[yello620]

So I have still been battling this problem. I have had it pressured up to 15 psi all night,and it only dropped maybe 3-4 psi. However I have a wet spot or two under the car. They are large,but not puddles per say. Also I have some green coolant on the top tank of the radiator at the lip. It is near the top radiator hose,but that connection is tight as hell. Also I see one wet spot on the passengers side of the car under the engine,and also it is wet around the fitting in the back of the head near the rear most spark plug. I tightened that hose fitting,but it still seems to be wet around there. Should I worry about these leaks if the pressure tester drops that little over that amount of time?

 

 

Chris

 

 

Yes, ANY fluid loss is a leak and it wont heal itself. It is leaking in spots because there is a problem and that problem will only get worse with time.

[Comfort Eagle]

Thing is I can't find where it is leaking,and I am not even sure if I am over pressurizing it,and causing the leak. So is 13 psi the system pressure? If so I have been putting more than that in,and maybe that is why it is leaking ever so slightly. It is frustrating though I can tell you that much.

 

Chris

[Comfort Eagle]

I was working on it this morning,and I found a pin hole in the upper radiator tank,and also it is leaking in the area of the intak manifold where it meats the head. I probably messed up the gasket some when I took off the header a few times,and the bolts weren't as tight as they should have been. Do I need a special gasket because I am using a header,or can I just get a stock style gasket? Where is the best place to get the gasket,and what can I expect to pay for one? Nissan part number would help if that is the best place to get the gasket.

 

Thanks,

 

Chris

[banzai510(hainz)]

A Felpro Brand intake /Exhaust gasket are common and about 10-15$ make sure to get the correct one as one is for the square exports and one for the round exhaust ports.

 

napa might have the gaskets also but I notice they dont sell the big port size gasket as the Felpro ones are already the 1.5 inch intake size.

 

Put gasket on with NO sealant anf evenly tighten the bolts up. You could to this now and see if it stops leaking and not cost you anything.

 

always get spares of everything as they will not stock this stuff anymore in most parts stores and esp in the east coast as not many Datsuns left due to salt erossion

[Comfort Eagle]

I also noticed this morning that I may have a small leak in the front most freeze plug on the intake/exhaust side of the engine,and I wiped everything down,and re-pressurized the system,and niticed the lower lip on that freeze plug had green coolant on it after a few minutes. How hard is it to get a freeze plug out,and do I need to get a special metric sized one from Datsun,or can I get one from Napa,or whatever local parts place I find?

 

I may have messed up the gasket on the intake/exhaust a little while ago anyway,as I was fed up with the progress of the SU install,and removed the header/ intake,and thought about going back to stock. When I removed the ehader teh gasket stuck some to it,and I thought I could get away with using it again as the material that was tsuck to it matched up perfect to itself. Maybe when I did this I damaged the gasket more than I though even though I never removed it from the block. I have been in the engine bay tightening up the bolts that are shared between the intake,and exhaust,and this has helped the leaking problem,but not solved it. Maybe it was a combo of the loose bolts,pin hole in the radiator,freeze plug,and the damaged gasket thast is causing this. The pin hole in the radiator is probably something I can fix myself as it leaks very little at 13-15 psi,and gets a bit more noticeable at 20psi,but I know the 20 psi is way too high for normal operation. I just hope the head is fin,and I am worried about the freeze plug. I really don't know how to get it out without pushing it in the block,and screwing myself.

 

 

Chris

[banzai510(hainz)]

chris the freeze plug is a 40mm I believe. Im like 99% sure.

If your sure the freeze plug is leaky youll have to drill a hole in the center and get a good sheet meatal screw and try to wedge it out(vise grips). I think I might have drilled so many holes in it too weaken it up then I hit it on one side w/hammer to cause it to PUSH in while the other side pops out then get the pliers or visegrips. But the guys at Napa will know how to do this also. The get new one clean with some fine sandpaper around the hole and put new one in gentrly and evenly. I dont know if you need sealant as the one I did I did not use any sealant. I was lucky it was on ethat is ez to get to. Dorman sells brass ones but I have seen steel ones also(rust).

 

 

The intake/exhaust gaskets you can spray Permatex Copperkote on there, This keeps the gasket from sticking if new. odf cause over time they all will stick to the head and ripp taking them off. I have used mine repeatedly a couple times in a week or so but after that I will always use a new one esp if it leaks. But on my beater I have the water lines plugged and dont use a heater linde as I have sidedraft carbs, But on my 521 I had a leak when swapping out motor tighten everything and was good to go.

 

also I have the early L16 510/521 exhaust manifolds and I am able to get to the lower bolts ezely with my hands. The Later L20 truck or car might have a different exhaust manifold and I know its a PAIN to get those lower bolts as it seems they design it not to be able to reach them. Even the stock carb bolts on the later L20s are difficult to get at.

 

 

Ps I antiseize all my bolts as it prevents rust issues also. but alway ck after installing the intake/exhaust bolts as I notice they do loosen up after a intake /exhaust gasket swap

[Comfort Eagle]

Is there anything that can be done to seal up the coolant passages better between the intake,and head? I ask because there isn't any sort of o-ring like on Mazda rotaries of certain years. Shouldn't the be some sort of o-ring,or something better than this simple flat gasket to seal up the water from leaking? What is the sequence to tightening the bolts on the intake/exhaust manifold so that it goes down flush,and doesn't leak?

[datzenmike]

W-58 head with round exhaust ports. Intake/exhaust gasket Nissan # 14035 W5800, about $20.

 

U-67 head with square exhaust ports. Intake/exhaust gasket Nissan # 14035 U6700, about $20.

[Comfort Eagle]

Thanks Datzenmike, W58 is the one I have. Is that the worst one to have? I ordered one from a friend at the local NAPA store,and it was a Fel-pro. I should have it tomorrow,and if it isn't the best quality then I will go by the local Nissan dealer.

[motavated]

I run my truck with red silicone on the intake gasket. I just place some silicone around the circles for the water passages on both side of the gasket and install. No leaking or problems yet.

[yello620]

Use a screwdriver and hammer to remove that freeze plug. Just hit it at one side and let it fall in, they come right back out when tipped a little sideways with a pair of pliers. Done this many times, Kinda scary until you have done one. Then its no big deal.

I always use a little bit of grey RTV sealer on the new freeze plug. Shouldn't need it, but it cant hurt either.

[banzai510(hainz)]

Some do have a copper O rings around the water passages.

But the Felpro ones do not.

 

I have no proplems just get it tight and evenly. esp with those thick exhaust washers. run the truck/car then ck after a few days