Rb26 Temp Rising And Falling Rapidly

[SCRMER]

Found the issue.

It was the head. The head wasnt exactly straight when it was taken off. It wasnt making proper seals around all the o-ring seals. To be honest, the head wasnt touched when it was pulled off the first time. It should have been checked before the motor got rebuilt.

It got sent away last week to get machined. A light machine on the underside, put it all back on and bam, normal temps.

Attention to detail was not there. Needless to say, not happy about it all. But everything is A OK now so what can i complain about.

Thanks all that tried to help

[Hadouken]

Great news. What a interesting dilemma.

Let's hope the motor lasts now.

[SCRMER]

So, as much as i hate to be posting this, the problem still exists. The head machining actually didnt fix the problem. Initially thought so but it is still there.

Motor basically got rebuilt again apart from taking the pistons and rods and still having the same issue.

All welsh plugs have been checked

Looks like there is definitely some sort of water flow issue.

From what i can see, i would pin point it to be a pump problem. Even though the pump has been changed and the old one used for testing. With the thermostat out, i can put a hose down the radiator, turn it on, and water will flow through the system if i keep a hose off and let it run out. Although it is weak, i am seeing water flow.

Turn the car on with the thermostat out, and the car on and nothing. Change pumps, same deal

Am i missing something? Is there some kind of potential valve somewhere that may be opening when we are putting pressure from a hose into the system to force the water out? Or does the RB need the thermostat in to open and let the water pass properly?

I am trying to get an idea of how water actually flows throughout the whole motor to try and eliminate everything i can

The above may be confusing so please ask questions if what i said doesnt make sense. It has been months and i cant take back ownership of my car after the motor has come out twice with the same issue!

[Hadouken]

They way I see it is,

Water flows through the system once the thermostat opens. With no thermostat then you have constant flow and very cold temps.

A question for you,

Have you tried running it with the heater on? Has it made a difference?

[SCRMER]

yep the whole time the heater is on, 32 deg, full blast, no hot air, barely any warm air even if car is over 100deg. Like water is not getting in there.

If you take off the hose and fill the heater hoses with warm water so it hits the core, it gets warm inside the car straight away.

Apart from the lack of flow without the thermostat in, when the car is hot and gets cool, you get hear hot and cold water hitting each other inside the motor when the car dramatically drops in temp.

Another interesting point is, the car just stays cold for so long, most likely cause the hot water is not flowing to hit the temp sensors

I am at a loss.

[Hadouken]

I have no idea what the go is with this.

What happens when you pressure test the cooling system?

I wonder if the only thing that can fix this is a new block....

[SCRMER]

Pressure tests come back fine.

The cooling system was A1 before the motor was pulled out for a rebuild.

I feel something has failed somewhere, something is blocked or there is some kind of value that isnt working correctly.

There is definitely a lack of flow in the system. What i feel is happening is water is just sitting in the system, it rises in temp, the thermostat opens, cold water from the radiator is just sitting there and there is nothing to push it through until some kind of pressure builds up that moves it manually.

When i took it for a drive around the block, i remember when it hit say 90deg and as soon as i turned a corner, it would drop in temp, like it had force to push the flow through. You'd think pump wouldnt you if there is no flow but water can go through the system?

Even when the water goes through to cool down, it never gets into the heater core, that's something interesting to note.

[scotty nm35]

If there is a rust blockage somewhere in the cooling system it needs to be cleared somehow, I would probably flush it with the hose then fill it with half vinegar and half water, that should eventually loosen any built up crap in the block and heater core or lines. Not sure how long to leave the vinegar in there, depends on the amount of crud, otherwise you will need to drop the engine again perhaps? It's worked for me in the past to break down the rust.

Did they acid dip the block when they rebuilt it?

[SCRMER]

Flow was fine before the rebuild.

Block was acid dipped, Everything was checked as best as during the build

is there any hose or anything that can be put on the wrong way or the wrong connection to cause flow from stopping.

But if flow is blocked then why can i force water through the system manually with pressure from a standard hose? But when the car is running on it's own, there is No flow.

We have pretty much done the same build we have done on other Rb26's i have had in the past. Just dont know what is different in this case or what has failed

Edited September 7, 2015 by SCRMER

[scotty nm35]

Someone leave a rag or something in the cooling passage or hose?

[SCRMER]

You'd hope not.

Is there any hoses or critical flow paths that can be connected up a different way by mistake or are things like the standard oil cooler sitting outside the main flow path and rely on the pressure in the system to push water through them?

[SCRMER]

Problem has now been resolved.

We initially changed the water pump again just to be sure. That didnt solve the problem.

Took the motor back out, and noticed that there was a row of inner welsh plugs on the exhaust side that were in. Apparently these are not meant to be in on a 26 and was restricting the flow of water in the block. I was told these were put in by the guy machining the block. But not here to play the blame game.

So took those plugs out, put the motor back together and perfect temps. Problem solved.

Thanks all for the advice, just wanted to provide and update so that this may help someone else in the future

Cheers

[GTSBoy]

wow

[GTSBoy]

And I mean that as in really wow, but also with an OMG I can't believe that was the answer, not just a flat deadpan wow.

[niZmO_Man]

Out of all the problems you could have had...

[SCRMER]

Yep it certainly is an uncommon one. Least one good thing has come out of this. It has identified what happens when you leave those plugs in

[iruvyouskyrine]

What plugs in particular are you talking about?

[GTRPSI]

Took the motor back out, and noticed that there was a row of inner welsh plugs on the exhaust side that were in. Apparently these are not meant to be in on a 26 and was restricting the flow of water in the block. I was told these were put in by the guy machining the block. But not here to play the blame game.

So took those plugs out, put the motor back together and perfect temps. Problem solved.

Inner welsh plugs in on the exhaust side that are not meant to be there?

What inner welsh plugs are there except for the one i pointed out under the thermostat on the intake side?

Pull all the welsh plugs out on the hot side and its just the inner block there, you cannot put inner plugs in if you tried as there is nowhere to fit them.

Unless he knocked to old plugs into the block when removing them and left them loose in there.

Id say you didn't get the whole truth........just the version of events that suited whoever told you.

[SCRMER]

Quite possibly so. I didnt see it, nor do i really know the inner workings on the block.

I'll dig a big deeper when i pick the car up tomorrow.