OEM Radiator Cap

[Bad Luck]

yes this is an old thread.
Yes I have read that should only use Toyota radiator cap.

However, when I got this fixer upper, had 306 and 420 codes and running on 4 cylinders. I did do a compression check, , a leak down test , and the chemical dye for the radaitor to test for exhaust gas, and all came back good. So with good results I did a full tune up ( plugs, wires, and a coil, cleaned maf and throttle body, that cleared the 306 code, new O2 sensor arrived but not put in, dont know how long they ran it on 4cylinders and dumped junk into cats. etc,) fluhed the cooling system, changed it from dirty green to red
The overflow tank cap fits funky, its aftermarket as what was on was a broken one wrapped in electrical tape. but its not uner pressure. right ? But it does seal, just dont like its fit. SO letting that slide for now. Will get toyota one in future.

So what Ive noticed is that the radiator will not suck fluid back into the radiator, but will push it into the overflow tank, so I occasinally top off the radiator, its not very much, maybe less than 2 or 3 oz to a tank of gas. And overlfow tank slowly rises and now is just barely above the upper line. Uses no oil ( recent change to synthetic). No discoloration in oil like water contamination. No excessive blow by when you take the oil fill cap off ( and running). No weird smell from exhaust, normal color exhaust, no smoking.

Could it be the non factory radiator cap ? Could I have something going on in my cooling system that tests did not show ? Could it be a leaking head gasket that does not show in tests ?

After getting up and running does not go above 1/2 mark on the gauge, and it coresponds to the torque pro ap that its running at correct temps. 275k on it now, ( ive put nearly 3k on it since buying and tune up) Due for timing belt and stuff in 10k, maybe a weeping waterpump, but i see no liquid underneath. Will also get a new radiator and oil cooler and hoses at the time.



thanks

If you're coolant overflow tank is only getting higher and not going up and down then I would suspect a faulty radiator cap. Radiator cap controls the in/out of coolant to the radiator as the engine cooling system heat cycles.

 

[Malcolm99]

If the overflow fills up but doesn't draw back down when cold and shut off I would suspect a leak in the system close to the rad or a main rad fluid hose(but a leak anywhere will cause this same symptom), usually the overflow to rad hose, main rad hoses or the rad cap, it should syphin the fluid from the overflow by vacuum as the fluid cools/contracts in this sealed system, if it's not drawing the fluid from the overflow while cooling down & shut off its sucking air from somewhere, this can also cause rad fluid to boil as it isn't under the pressure it would normally be which lowers the boiling temp, a proper mix of rad fluid and water will raise the boiling temp as would higher system pressure.

 

[3bears]

thanks, guess I will bend over and at the same time I will get out my credit card and hit the stealer for a new cap. I have air miles on the card....so that will help get me too Hawaii, might even be enough to move me to 1st class
let me see, prob cost the dealer about $3 so I should expect to pay about 30.

sorry about the attitude

I will get a crap from dealer and see if that helps, but might be a few days b4 I get it and post results

also...for fun...in the posts above have pictures of dealer supplied rad caps, both have "D" on them...like maybe denso ?
However you go to ebay or amazon and look at "genuine" radaitaor caps, none have the "D"

 

[19963.4lsr5]

I had zero problems with the three napa caps I purchased.

All three 3rd gens I bought had broken caps.


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[3bears]

I had zero problems with the three napa caps I purchased.

All three 3rd gens I bought had broken caps.


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well whats on is a "stant" fromm what I can tell its 16 lbs. will check NAPA . the napa one is rated at 13 pounds and just says belknap. Cant imagine that pound difference would be part of it, or could it ?
glad yours is working, thats good to know.
I also wonder , the hose inside overflow is a fuel hose ( thats what was on it) seems to fit snug but I can easily spin it even with the zip tie thats on it ( from previous owner.), but maybe it is not sealing and not sucking fluid up. Maybe I should replace that first and see. If that works for now, will just wait till spring when I replace radiator and get a "real" cap. ( will be doing timing belt and pump, etc at the time.


thanks for your help/advice

 

[19963.4lsr5]

I would get a new hose from the rad to the tank and replace the cap and tube going into the tank. You shouldn’t be able to freely spin it.


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[3bears]

I would get a new hose from the rad to the tank and replace the cap and tube going into the tank. You shouldn’t be able to freely spin it.


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The hose from rad to tank is prob original, but Ill replace that too. The cap on overflow ....wonder how quality of aftermarket is for those. Napa has them in stock.
Are the hoses anything special, other than maybe a vacum type hose so does not colapase when sucking fluid back to radiator ?

thanks

 

[Malcolm99]

It Isn't reinforced hose, so similar to large vacuum line, it is passively syphoning fluid so no chance of collapsing the rubber lines, the overflow cap doesn't need to seal to the overflow tank but the hoses connecting to the over flow cap side, bottom and to the rad must be sealed to create the slow passive syphon affect to draw the fluid back into the rad as the fluid contracts. Ofcourse a crack overflow cap would be problematic, but you can easily remove this assembly and test for a leak, since the syphone effect is so slow and passive a small leak in the system anywhere will eliminate the syphone effect. Stant is usually good, but a leak at the rad cap would cause this issue aswell.

 

[19963.4lsr5]

The hose from rad to tank is prob original, but Ill replace that too. The cap on overflow ....wonder how quality of aftermarket is for those. Napa has them in stock.
Are the hoses anything special, other than maybe a vacum type hose so does not colapase when sucking fluid back to radiator ?

thanks

I wouldn’t have a problem using the napa overflow tank cap.

Any hose that fits tight under the tank cap should be ok.


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[3bears]

thanks all
I will get a new hose and cap, but might wait till it gets to above MINUS 30. Otherwise not gonna pop the hood right now. No visable fluids in the snow when i move it to take my grandaughter to school.
supposed to get above zero in a few days again and I will mess wtih it then but also need to get back to work on a outside
new construction currently non heated 2 story building. It was above zero when I started this question. I usually check my fluids every few days on this old rig,, more than daily if I know i have an issue. 2-4 oz of antifrezee loss on a tank of gas is not a major issue for me today yet I need to know what is happening so I can sleep at night and not worry about this old girl. ( and not worry while I drive on a timeline for my grandaughter to school)


but thanks guys..I mean that....will update soon
thanks

 

[T4R2014]

The hose from rad to tank is prob original, but Ill replace that too. The cap on overflow ....wonder how quality of aftermarket is for those. Napa has them in stock.
Are the hoses anything special, other than maybe a vacum type hose so does not colapase when sucking fluid back to radiator ?

thanks

I have an aftermarket overflow cap, I think Dorman. Horrible. It is slightly smaller and requires gorilla force to get it on the bottle.

 

[Malcolm99]

Hopefully you work it out, Rad fluid loss is always a bit of concern in cold climate, as long as the suction is good from overflow to rad I would look elsewhere for a leak, my original rad cap says ND for Nippon Denso to add to the list, maybe I should think about replacing that and the ECT sensor lol, 191*F normal temp cruising though on SgII, Yellow Prestone rad fluid going on 6-7 years now, IAC and t-stat coolant internals looked like new when I checked this winter.

 

[19963.4lsr5]

I have an aftermarket overflow cap, I think Dorman. Horrible. It is slightly smaller and requires gorilla force to get it on the bottle.

Dorman is the last aftermarket company I use. And only if I’m desperate.

I prefer Napa and anything made by BDW for replacement parts that I don’t choose OEM for.


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[T4R2014]

Dorman is the last aftermarket company I use. And only if I’m desperate.

I prefer Napa and anything made by BDW for replacement parts that I don’t choose OEM for.


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Pretty sure Dorman and Napa just buy the same crap from a factory in China. Napa is usually the better bet for auto store chains but occasionally they get junk too.

 

[TheDurk]

Pretty sure Dorman and Napa just buy the same crap from a factory in China. Napa is usually the better bet for auto store chains but occasionally they get junk too.

NAPA's Altrom line is frequently just the OE manufacturer product rebadged. If not, it's still good stuff. Echlin line is not Chinese junk. Straight NAPA brand you takes your chances, but better than most places. NAPA filters are made by Wix. (That's good.)

I use a lot of NAPA stuff and I can't remember the last problem I had.

 

[T4R2014]

NAPA's Altrom line is frequently just the OE manufacturer product rebadged. If not, it's still good stuff. Echlin line is not Chinese junk. Straight NAPA brand you takes your chances, but better than most places. NAPA filters are made by Wix. (That's good.)

I use a lot of NAPA stuff and I can't remember the last problem I had.

Usually. My only experience with Echlin was the PCV valve and it was exactly the same as the Purolator they sell at autozone. I'd eventually get the oil burning issue again and fix it with an OEM. Napa does tend to get the better stuff though, and you just can't get service like they provide in an auto store anymore. Those are real parts guys.

 

[3bears]

fixed
replaced the hose in overflow with one that fits tight (5/16 vacum) and the hose from rad to overflow cap.
seems to fix the problem.

 

[Nology]

Just ordered
Just ordered part number 16401-36020 from camelbacktoyota. Does this cap have the Japanese writing on it or does it look like what’s on the pic. I may cancel the order if this is what it looks like. It’s for my 2001 4runner. a¥

2001 SR5 4x4 Premium
2017 SR5 4x4 Premium

I picked up a new Denso Japanese radiator the other day and didn't think it would come with a cap so I ordered one. Apparently, people forgot how to read at some point and Toyota revised the label.