Cylinder Head questions

[Linda]

Pierre,
Here in California several auto parts store loan tools for a deposit, and the exhaust coolant tester is one of them . They even supply the fluid that you use in the tube at AutoZone .Quite a useful tool if you can find one.
Or just pay a mechanic to do the test. Has to be a leak somewhere...
Linda

15874972118840.jpg

[Pierre]

When was the head last retorqued? Sometimes a retorque can stop a small leak. Check archives for info.
Linda

That's hard to say I bought the car last year, the frame was redone and repainted but the engine not.
I am the 1st owner who drives it in Europe, It came originally from the US, like most of them, so can't tell

[Pierre]

So, both 1 and 2 are burning coolant from some source, either the head gasket or the intake manifold. The tell will be a compression test. That should be an easy tool to locate or borrow. Let's hope they're all within 10lbs or so of each other! If that's the case, then I'd look towards your intake manifold. The bottom nuts are hard to get tight and the washers don't always engage as well as you'd like. You'll have to pull the intake to remove the head anyway, so messing with it first is not wasted time. Check the nuts under there.
A careful retorque of the head may help too as Linda suggested. Keep poking!

I will do a compression test for sure.
at what pressure should I test the radiator ? Do I have to remove the thermostat ?

[Pierre]

Pierre,
Here in California several auto parts store loan tools for a deposit, and the exhaust coolant tester is one of them . They even supply the fluid that you use in the tube at AutoZone .Quite a useful tool if you can find one.
Or just pay a mechanic to do the test. Has to be a leak somewhere...
Linda
15874972118840.jpg

I guess I have to try this too ...

I'll check if some one can borrow me one.

Thx Linda!

[redroadster]

A tech at my Datsun dealer in the 70s would put headgaskets on in just over ah hour on 1600s
Because he only pulled headbolts ...then with the engine crane lift up the head 5/16th , with a flexy fillet like knives
Loosen the gasket which may have only been on a few yrs
Pull it out R side clean for 15 min. same way in sprayed with copper coat. Do not think he had any trouble with them .He took the main engine job away from the old guy that had it
I did this on on a 210 I bought to sell .and. some Renault Alliances

[Gregs672000]

I have seen but not used the coolant sniffer being discussed. I don't believe you need pressure in the system. I believe that what it's doing is taking a sample of the coolant and chemically checking for exhaust products being in the coolant itself, indicating a compromised head gasket. Sometimes a head gasket isn't compromised enough to show clearly with a compression test. But I'd start with compression... cheap tool and useful. I don't recall, has the engine overheated?

[Linda]

The coolant sniffer is not supposed to touch the coolant, that is why you drain down the level. I don’t know how to use it on a u20, guessing you could use the radiator fill, so no need to remove thermostat. Instructions are with the tool
Linda

[Gregs672000]

Yes, sorry... I wasn't precise... it's sniffing the fumes, not sampling the fluid itself.

[Pierre]

Hi,

I hope you are all fine?

so little update,

I finally managed to do the tests.
So I did the radiator exhaust gas test, the cylinder compression test and the radiator compression test.
the 2 first went well. So no exhaust fumes in the radiator an good cylinder pressure ( at least I hope so, the picture is the cylinder test, let me know if it is fine)
But there is a coolant leak as some of you already suggested in the intake manifold.
So I will change the gasket in the next days and see if everything works again.
Is there anything specific I should know about this fix ?

Pierre

[david premo]

Hi Pierre,
The numbers are ok a little low but not bad. Did you do the test with the throttle wide open and lifting the slide as well? If not retest with the throttle wide open and the slide held up. 12.6 bar would be a better number. Be sure to check the inside of the manifold runners as it could be possible that it has corrosion between the runner and water passages. Additionally it could be the manifold is not sitting flat to the cylinder head. Good luck!
Dave

[Gregs672000]

Yeah, that beats the heck out of pulling the head for a bad intake gasket! As Dave said, there are specific things that need to be done to get a full compression test (warm engine, plugs out, wide open throttle with the piston up on SU carbs, good battery) but for our purposes here what you did was fine, and you determined that the head gasket is not leaking, cylinders are all about equal... well done!
The hard parts about doing the intake gasket is mostly about accessing the nuts. There's very little room for both hands and wrenches, and I've found that one 13mm wrench can have a better angle than others. The 13 I use is thin, and the boxed end is angled and thin walled as well. This allows you to get onto the nuts easier. There are thick washers that must go on as well, as they contact the raised tabs on the intake and header/exhaust manifold and clamp it down. Be patient, be prepared to be bending over the car for some time, have a good flashlight and a small inspection mirror so you can kinda see what you're doing, take a break if it gets to you. I've done them so many times now they're not a problem, but the first time you do anything it's a learning process about what works and what doesn't. You will need to drain the rad, and depending on the exhaust manifold and it's willingness to move off the studs, it may need some loosening at the collector. I usually run a dye over the studs to clean up the threads, making it easier to hand spin the nuts as far as possible before needing the wrench. You can remove a nut off the end of the exhaust manifold to take as a thread and pitch sample to the hardware store to select the right dye. The stock washers mentioned can be quite thick. I've resorted to thinner washers before but they can bend some, so if you decide to replace them choose something that's thick and strong enough to do the job. Remember that something was probably not done quite right that allowed it to leak, so take note as you go through it for what might have not worked right to create a seal. You know that is 1 and 2 cylinder, so be observant there.

Onward! Post back with your success or struggles... we're here for both!

[Linda]

I wondered if perhaps some coolant could be leaking elsewhere too. The freeze plugs on the driver side could push some fluid out if rusted. That block drain plug on driver side might leak. Check to see if any fluid is hitting the exhaust or collector. I know it is coming out the tail pipe but you had some white smoke from engine bay also. Might as well check condition.

Linda

[Pierre]

Yeah, that beats the heck out of pulling the head for a bad intake gasket! As Dave said, there are specific things that need to be done to get a full compression test (warm engine, plugs out, wide open throttle with the piston up on SU carbs, good battery) but for our purposes here what you did was fine, and you determined that the head gasket is not leaking, cylinders are all about equal... well done!
The hard parts about doing the intake gasket is mostly about accessing the nuts. There's very little room for both hands and wrenches, and I've found that one 13mm wrench can have a better angle than others. The 13 I use is thin, and the boxed end is angled and thin walled as well. This allows you to get onto the nuts easier. There are thick washers that must go on as well, as they contact the raised tabs on the intake and header/exhaust manifold and clamp it down. Be patient, be prepared to be bending over the car for some time, have a good flashlight and a small inspection mirror so you can kinda see what you're doing, take a break if it gets to you. I've done them so many times now they're not a problem, but the first time you do anything it's a learning process about what works and what doesn't. You will need to drain the rad, and depending on the exhaust manifold and it's willingness to move off the studs, it may need some loosening at the collector. I usually run a dye over the studs to clean up the threads, making it easier to hand spin the nuts as far as possible before needing the wrench. You can remove a nut off the end of the exhaust manifold to take as a thread and pitch sample to the hardware store to select the right dye. The stock washers mentioned can be quite thick. I've resorted to thinner washers before but they can bend some, so if you decide to replace them choose something that's thick and strong enough to do the job. Remember that something was probably not done quite right that allowed it to leak, so take note as you go through it for what might have not worked right to create a seal. You know that is 1 and 2 cylinder, so be observant there.

Onward! Post back with your success or struggles... we're here for both!

Wow thank you very much for the detailed instructions and tips!!!
I followed your advises...
I have the intake off. an now my back and fingers hurts
The gasket looks fine actually, but if I am not mistaken in at least one of the intake chambers (picture) you can see green coolant.
So I guess it is getting in somewhere.
And of 4 intake chambers just one is dry 3 are wet. Is this coming from a bad carburetor adjustment ?

[Gregs672000]

Interesting, can you post pics of the other three, and maybe one that shows the intake side of the engjne?

[Pierre]

Interesting, can you post pics of the other three, and maybe one that shows the intake side of the engjne?

So here are all 4, front to back