Cooling system issue

[Banjo]

Hi Viterbo,

                  Just looking at your pic of the Pimera radiator.

 

I'm presuming that your line to your overflow/expansion bottle, is connected to the spout circled on the RHS of the above picture.

Is that round bit directly below where the radiator cap fits on, a "bleeding" point for the coolant ?  Looks to have a hex socket in the plastic, so could be screwed out. 

Is the point where the spout comes out of the Pimera radiator the same distance below the top, as the spout on the K Series radiator ?

If the new Pimera radiator cap, does not solve the problem, then the question arises, why is the system not pressurising, when you unlock the radiator cap after running, & there is no pressure exhaust obvious ?

That can only mean that the coolant system is not sealed elsewhere, & is not allowing the system to pressurise.

Have you hooked up a cabin heater or anything other coolant line elsewhere ?  There aught to be a leak displaying somewhere.  If no, then the only other explanation can be an internal leak, within the engine itself., which is serious. Check oil level & discolouration etc.

I do hope the new Pimera radiator cap solves the issue, because if not, I would not run the engine, until you solve the issue, for fear of damaging the engines internals.

Cheers Banjo

 

 

 

 

[altezzaclub]

Just measure the distance from the top of the radiator, where the cap locks on, to the sealing shoulder down inside the neck.  Make sure both radiators have the same distance for the cap spring to get compressed, as the photo looks like the Primera rad has a much taller neck. Diameter of the cap seal the same??

One way or another, if its not the head gasket I'm sure its the cap sealing that is at fault.  A leak would be very noticeable and it wouldn't fill the overflow bottle if it was losing pressure through a big leak.

[Viterbo]

Checked the measurements and both diameter of the top and depth are the same, same cap is used on both radiators.

Bled the system once again with my bleeding funnel, after the thermostat opens a couple of times just really small bubbles every now and then appear. Oil is perfectly fine, no milky substance in the oil cap, nothing.

Since they're the same, after I bled the system I installed the new "TRD" radiator cap I had laying around.

Need to go for a run to see any improvements.

[LittleRedSpirit]

Putting 2 and 2 together, you see small bubbles after bleeding with the cap off at idle, it ejects the coolant at higher rpm.  It could well have a blow from combustion pressure to water jacket that wont affect oiling, it will just pressurise the heck out of the cooling passages at higher revs and cylinder pressures.  Compression test the engine.  Pressure test the cooling system at the same time and see how much pressure in the water jacket coincides with compression events in the engine.  If there's any correlation you will have your answer.

[Banjo]

Hmmm !   Not looking good.   When you "rebuilt your 5K" did you . . . .

Skim the top of the block ?

Skim the head ?  

Repair any corrosion around any of the water jacket transfer holes in the head ?

Use a new head gasket with built in sealant bead around the water jacket transfer holes ?

Ensure you fitted the very heavy/thick washers back under each head  bolt ?

The LittleRedSpirit man's suggestions are now your best suggestion, of getting to the source of this problem, now that we have ruled out the other more common, easily fixed ones.

Let us know what you find.

Cheers Banjo

 

 

[Viterbo]

Yep, block skimmed, head skimmed, good gasket, bolts ok.

It does this since day 1 after the rebuild that was also the start of this radiator use. I hardly believe it's engine related.

I'm still yet to test the new cap.

[Banjo]

Hi Francisco,

                       I'm finding it hard, to think of anything else related to the radiator change, that could cause all these issues, if the use of the new Pimera radiator cap, does not change or solve anything.  As you have advised, this problem has been there, right from the first start, after the engine rebuild, I'm left with no other answer than it is something in the engine.

The only way you can completely prove this to yourself, is to fit back the original K series radiator, as you suggested. If it still happens, then it is the engine.

I seem to remember a post where you were considering porting the head slightly. Is there any possibility, that you have taken too much out, & you've got a crack or tiny opening, into the water jacket it the head ?  

Something like that, could certainly cause a problem, similar to what you have described.

Cheers Banjo

Edited June 17, 2019 by Banjo

[ke70dave]

Just remember that you can do a cooling system pressure test to make sure the headgasket is not the issue. (if it gets that far) My mate has the kit, you put it on the radiator cap and there  is a hand pump and you pump it up to whatever your radiator cap is. Let it sit for 30mins and see how it goes. 

[Viterbo]

So I was only able to test the new cap yesterday, it was raining and I went for a slidding run, so I pushed the car a bit.

So far so good, the stock expansion bottle didn't fill as it was doing before. Seems the issue really was a faulty cap.

[Banjo]

Hi Francisco,

                       Very glad, to hear it was something so simple, & nothing like a head gasket or a breakthrough into the water jackets anywhere.

 

Cheers Banjo