I've been having trouble with my radiator filling up with air. I thought it was simply that bleeding the system is difficult and it's just been getting airlocked. But having to bleed air out of the radiator more and more regularly has made me face the reality that something else must be wrong.
I made sure to thoroughly bleed the coolant system and then took the car for a decent run to see family. When I checked the radiator again, it had filled up with air once more.
Recently I have seen oil weeping from both the head gasket and rocker cover gasket, possibly due to overheating. I think it's also down on power.
It doesn't seem to be using much oil. And there isn't coolant in the oil, or oil in the coolant.
I've ordered a compression tester and a block tester (gasses in coolant indicator), so I'll be able to find out for sure.
My question is therefore not 'has the head gasket gone?' but 'what should I do about it?'!
I believe the damage was done when the radiator failed. It shook itself apart shortly after fitting coilovers. I didn't notice immediately, and when I did I still needed to drive it a little way home. Following this there was an oil leak from the rocker cover gasket; which I thought was a rather easy fix! Replacement radiator and coolant and all seemed to be well for a few months.
Is it worth me changing the head gasket or is the engine for the bin?
What radiator did you fit? Some of the pattern ones are prone to leak on the bleed screws and it doesn't take much to get air in the system.
When you say the rad had "filled up with air" how much coolant had you lost?
Just an ebay pattern part https://www.ebay.co.uk/itm/150561877372?fits=Model%3AMR2&hash=item230e2fed7c:g:b1YAAOSwX6xg9-r6
I did actually try and get an uprated Mashimoto rad from Demon Tweeks but they had no stock.
It's quite hard to tell if it's losing any coolant because the filler tank only drops once I bleed the radiator, and I always lose some coolant when bleeding the radiator. It can't be much. And I haven't seen any obvious leaks.
Did you bleed the pipework not just the rad bleed point?
Norman
Yes, I did the heater matrix bleed point as well as the rad. With the engine running and blowers on hot.
Are there any others?
It maybe indicative of OCD on my part but when I changed the coolant in my 2 I flushed the system very thoroughly and then checked/ measured what came out was equal to the theoretical capacity. Satisfied the system was as empty as I could make it I put a measured amount of new coolant into the system. There was a partial airlock preventing the full theoretical amount of refill indicated by an empty expansion bottle. Using the the remainder of the measured refill resolved this.
Just those 2 Shadowsoul, last time I bleed mine it took just 5 mins - that was after I lost a hose when the clip failed and I lost about half my coolant.
Norman
Quote from: ShadowSoul on January 5, 2022, 21:19Yes, I did the heater matrix bleed point as well as the rad. With the engine running and blowers on hot.
Are there any others?
There are two drain/ bleed points on the coolant pipes just front of halfway along the underside of the car.
I would get an oil analysis done as soon as possible. You will know for sure if there were any trace amounts of combustion gases or coolant clearly indicating head gasket failure.
Quote from: Joesson on January 5, 2022, 22:24Quote from: ShadowSoul on January 5, 2022, 21:19Yes, I did the heater matrix bleed point as well as the rad. With the engine running and blowers on hot.
Are there any others?
There are two drain/ bleed points on the coolant pipes just front of halfway along the underside of the car.
I've heard they are prone to shearing when half-way out.
Quote from: Gaz mr-s on January 6, 2022, 10:28Quote from: Joesson on January 5, 2022, 22:24Quote from: ShadowSoul on January 5, 2022, 21:19Yes, I did the heater matrix bleed point as well as the rad. With the engine running and blowers on hot.
Are there any others?
There are two drain/ bleed points on the coolant pipes just front of halfway along the underside of the car.
I've heard they are prone to shearing when half-way out.
I was going to add to this to say only ever touch these if they're definitely leaking, the heads sheer as soon as you look at them.
I'm pretty sure I did drain the coolant at those two screws. I remember reading that they shear easily, and then was surprised that they loosened without incident.
Quote from: Call the midlife! on January 6, 2022, 11:03Quote from: Gaz mr-s on January 6, 2022, 10:28Quote from: Joesson on January 5, 2022, 22:24Quote from: ShadowSoul on January 5, 2022, 21:19Yes, I did the heater matrix bleed point as well as the rad. With the engine running and blowers on hot.
Are there any others?
There are two drain/ bleed points on the coolant pipes just front of halfway along the underside of the car.
I've heard they are prone to shearing when half-way out.
I was going to add to this to say only ever touch these if they're definitely leaking, the heads sheer as soon as you look at them.
Having read a similar report I was pleasantly surprised that the first time I removed those drain screws, around 2015, it was not a problem, nor was it last year. I had put a dab of Coppaslip on the threads as is my standard operating procedure for things that may go tight over time.
Those screws that have been damaged on removal may be due to some corrosion build up, if a thread starts to tighten up when fitting or removing, it is good practice to back off and try again to help break up such corrosion or other interference rather than keep on turning against resistance until something gives or breaks.
Quote from: Joesson on January 6, 2022, 13:32Quote from: Call the midlife! on January 6, 2022, 11:03Quote from: Gaz mr-s on January 6, 2022, 10:28Quote from: Joesson on January 5, 2022, 22:24Quote from: ShadowSoul on January 5, 2022, 21:19Yes, I did the heater matrix bleed point as well as the rad. With the engine running and blowers on hot.
Are there any others?
There are two drain/ bleed points on the coolant pipes just front of halfway along the underside of the car.
I've heard they are prone to shearing when half-way out.
I was going to add to this to say only ever touch these if they're definitely leaking, the heads sheer as soon as you look at them.
Having read a similar report I was pleasantly surprised that the first time I removed those drain screws, around 2015, it was not a problem, nor was it last year. I had put a dab of Coppaslip on the threads as is my standard operating procedure for things that may go tight over time.
Those screws that have been damaged on removal may be due to some corrosion build up, if a thread starts to tighten up when fitting or removing, it is good practice to back off and try again to help break up such corrosion or other interference rather than keep on turning against resistance until something gives or breaks.
I think most of the problem lies in the access to them if you're not on a ramp/fully underneath the car. If you try reaching in from the side you're at full stretch and can't tell if it's the screw turning or head twisting until it's too late.
Quote from: Call the midlife! on January 6, 2022, 13:50Quote from: Joesson on January 6, 2022, 13:32Quote from: Call the midlife! on January 6, 2022, 11:03Quote from: Gaz mr-s on January 6, 2022, 10:28Quote from: Joesson on January 5, 2022, 22:24Quote from: ShadowSoul on January 5, 2022, 21:19Yes, I did the heater matrix bleed point as well as the rad. With the engine running and blowers on hot.
Are there any others?
There are two drain/ bleed points on the coolant pipes just front of halfway along the underside of the car.
I've heard they are prone to shearing when half-way out.
I was going to add to this to say only ever touch these if they're definitely leaking, the heads sheer as soon as you look at them.
Having read a similar report I was pleasantly surprised that the first time I removed those drain screws, around 2015, it was not a problem, nor was it last year. I had put a dab of Coppaslip on the threads as is my standard operating procedure for things that may go tight over time.
Those screws that have been damaged on removal may be due to some corrosion build up, if a thread starts to tighten up when fitting or removing, it is good practice to back off and try again to help break up such corrosion or other interference rather than keep on turning against resistance until something gives or breaks.
I think most of the problem lies in the access to them if you're not on a ramp/fully underneath the car. If you try reaching in from the side you're at full stretch and can't tell if it's the screw turning or head twisting until it's too late.
Indeed, always best to see what you are trying to do, not advisable to drive with your eyes shut.
The block tester kit arrived so I've had a go at testing the coolant for exhaust gases.
There was no colour change which means no leak detected. I'm surprised at that result. I'll do a compression test when the kit turns up and hopefully get a better idea what's going on.
I suggest the O rings on the drain and bleed screws on the radiator are not holding back air. I've come across this before. They prevent obvious water leaks, but when the radiator cools air can get sucked back in.
Because the inlet and outlet on the radiator are both halfway up (strange design), an air pocket can build up in the top half of the radiator. The bigger the air pocket, the more it will suck back as temperature drops and the air contracts. I bought some 6mm O rings that are slightly fatter than the ones that come with the radiator and found they did the job. No guarantee in your case, but any air leak around the radiator end of the cooling system will create an ever-growing air pocket in the rad.
Any coolant leaking into the combustion chamber should result in some fouling of the spark plug. Are all the plugs the same colour. Does one stand out as looking 'different'? A very small coolant leak across the head gasket may not show up in a coolant test or, indeed, a compression test.
Can you drop out all the coolant, then do a leak down test of the coolant system?
That would tell if/where you are having air ingress.
Quote from: Carolyn on January 7, 2022, 13:46I suggest the O rings on the drain and bleed screws on the radiator are not holding back air. I've come across this before. They prevent obvious water leaks, but when the radiator cools air can get sucked back in.
Because the inlet and outlet on the radiator are both halfway up (strange design), an air pocket can build up in the top half of the radiator. The bigger the air pocket, the more it will suck back as temperature drops and the air contracts. I bought some 6mm O rings that are slightly fatter than the ones that come with the radiator and found they did the job. No guarantee in your case, but any air leak around the radiator end of the cooling system will create an ever-growing air pocket in the rad.
Any coolant leaking into the combustion chamber should result in some fouling of the spark plug. Are all the plugs the same colour. Does one stand out as looking 'different'? A very small coolant leak across the head gasket may not show up in a coolant test or, indeed, a compression test.
Thanks for the info. It seems plausible that the radiator could be the problem.
I'll check the spark plugs when I do the compression test.
I have carried out the compression test (I found a useful guide here (https://www.spyderchat.com/threads/how-to-compression-check.18141/)). Results don't look too bad:
cylinder 1 = 167psi
cylinder 2 = 165
cylinder 3 = 160
cylinder 4 = 165
This was conducted cold. I'm led to beleive a test when the engine's warm would give slightly higher results?
The spark plugs also look ok. So there's no indication that the head gasket is leaking after all. Which is a relief (although I might have been looking for an excuse for an engine conversion).
Is it sporadic overheating due to the cooling system getting airlocked that has caused the rocker cover gasket to leak oil? Is there any other damage I should be watching out for?
I'm think I'll change the rocker cover gasket and radiator again, this time for a genuine article, and see how it goes.
Are you sure the leak is from the rocker cover and not the chain tensioner?
The plugs look ideal for burn colour, although the gap seem a tad large (could just be the photo).
There's definitely oil coming from the cam cover. You can see it collecting in the picture I took.
The oil further down the block could also be from there, or potentially from the tensioner, although I did change the o-ring already.
As for the spark plugs, I never check the gap I just trust the size I buy. Might be the wrong thing to do!
Thanks for the help.
Yep, you're right about the cam cover. Avoid the blue gaskets!!
If you used a Toyota O ring on the tensioner, it will probably be leaking. They are pants.
I have some that the club provides at no cost. They are a tad fatter and do the job.
Send me PM and with your address, and I'll get one off to you.
Yep, the exact spot that Foxy had the leak too - all sorted with the proper part! ;D
Ok so it's been a while. It's taken a while to do the next steps.
Thanks for the offer of a replacement o-ring, Carolyn. I think I have a viton o-ring somewhere. It took so long to arrive that I just fitted an OEM one from MR2Ben. I'll try swapping it.
I bought a genuine radiator from Toyota (£250!), fitted it and bled the system. Unfortunately it still seems to be trapping air in the rad.
I had a realisation that the gasket leak test kit might not be encountering any gases at the expansion tank, since they are being pumped to the radiator and collecting there. I bodged together a bubbler/adapter to collect the bubbles from the rad and test them. The results were firmly inconclusive. If you look at the pictures, the colour indicating solution changed fractionally from blue to blue-green. It's supposed to turn yellow to indicate exhaust gases.
After driving it for a few days I thought I would try collecting the gas from the rad to see how much there is. I'm not exactly sure what I hope to achieve, I'm just curious.
Using an upturned jug in a bowl I measured just about 100ml. Interestingly, no air came out when I first opened the bleed screw (with the expansion tank open), air only came through when I started the engine.
I've reset the trip odometer and drawn a line on the expansion tank. In a while I'll look again to find out how quickly the gas is collecting and whether it is losing coolant. At the very least maybe I can estimate how far I can drive before the coolant return pipe starts sucking air.
Any other ideas how I can determine what's going on? Is it time to admit I need a mechanic?
Have you changed the O rings on the radiator bleed and drain?
No. Just whatever came on the toyota part.
I'm not expert but if you're trying to bleed it with the expansion tank open you're not going to be pressurising the system, you're also at risk of losing coolant by boiling out of the expansion tank.