Bubbles in the coolant tank, blown head gasket?

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HypnoToad
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Model: Excel
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Year: 1984

Bubbles in the coolant tank, blown head gasket?

Post by HypnoToad »

Hi everyone, first post here, I've recently picked up a 1984 Excel and it's a great car, but the one I have needs a little TLC.

I found the valve shims needed sorting as I thought I may as well check the clearances while trying to fix a cam cover oil leak. With the valve clearances done, it seems to run quieter especially from cold. 8)

However, I'm getting bubbles in the coolant expansion tank when the engine is warm, here's a quick video:
https://www.youtube.com/watch?v=nZb4TmIiDcQ
(ignore the white smoke, I still haven't fixed the cam cover oil leak) :roll:

So far I've:
- pressure tested the cooling loop to 1.5 bar and there are no leaks when cold.
- done a cylinder compression test and all cylinders are around 10-11 bar.
- checked water in the oil and it looks OK
- checked for oil in the water, again seems fine
- checked the torque on the cylinder head bolts (while doing the valve shims)

I've not taken the head off yet, I'm 90% sure it needs a new head gasket, but I was wondering if there's anything else to check before I strip the engine down again.

Basically, if this isn't a leaky cylinder head, what else could it be?

Cliffords
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Re: Bubbles in the coolant tank, blown head gasket?

Post by Cliffords »

Looking at the colour of the coolant and the bubbles I think that is a failed head gasket

Pete Boole
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Re: Bubbles in the coolant tank, blown head gasket?

Post by Pete Boole »

How about doing a combustion-gasses-in-coolant test? They are cheap and easy to do.

Pete

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rbgosling
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Re: Bubbles in the coolant tank, blown head gasket?

Post by rbgosling »

Welcome HypnoToad, glad you're enjoying your Excel, and I hope you aren't too put off by the initial problems!

Assuming it is a gasket and you are going to do a change, some things to note:
  • It is possible to do this with the engine in the car, even though it's on a 45deg slant.
  • The most awkward bit is the exhaust manifold, which is damned near impossible to separate from the head with the engine in the car. Some have just about managed, by undoing the engine mounts and jacking the engine up a bit. I went the other way, and separated the manifold from the downpipe, and pulled the head out with exhaust manifold still attached.
  • On which subject, this is a good opportunity to replace the manifold studs with stainless, and their nuts with brass. The originals are probably rusty stumps by now.
  • Also on the subject of replacing stuff, do the cam belt. Unless you are certain it's been done recently, this is always worth replacing on a car just acquired.
  • Of course, while the head is off, there's always the temptation to give it a light skim to ensure it's flat; re-cut the valve seats; grind the valves, or just fit new ones; check the cam profile isn't worn; polish the ports etc. etc.
  • New head studs aren't a bad idea, too.
  • Make sure the head and block face are super super clean when you re-assemble. I shouldn't have to say this, I'm sure, except I do, because it took me 3 goes before I did it right. Don't be like me.
"Farmer" Richard

1990 Lotus Excel SE (Lilith)
2022 MG MG5 EV (not due to be a classic for quite a few years...)

HypnoToad
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Re: Bubbles in the coolant tank, blown head gasket?

Post by HypnoToad »

Cliffords wrote:
Tue Apr 26, 2022 23:01
Looking at the colour of the coolant and the bubbles I think that is a failed head gasket
Yep, I'm struggling to think of what else could cause this if it's not a failed head gasket, other than a cracked head but I really hope it's not that!

I've only filled it with tap water for now for testing, I plan to drain and fill with the recommended coolant once the issues have been sorted.
Pete Boole wrote:
Wed Apr 27, 2022 09:26
How about doing a combustion-gasses-in-coolant test? They are cheap and easy to do.

Pete
Thanks, I wasn't aware of these, I've ordered one today and will see if the blue fluid stays blue or not once it arrives.
rbgosling wrote:
Wed Apr 27, 2022 12:07
Welcome HypnoToad, glad you're enjoying your Excel, and I hope you aren't too put off by the initial problems!

Assuming it is a gasket and you are going to do a change, some things to note:
...
Thanks the info, especially the part about being able to get the head off without removing the engine. I've already got a new cam belt to go on, but will go for some new head bolts, as it looks like my bolts are not the revised dimpled ones.

For a car that's almost 4 decades old, I think it's fair to expect an few problems, so I'm not too put off so far!

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DavidOliver
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Re: Bubbles in the coolant tank, blown head gasket?

Post by DavidOliver »

If you have the cylinder head out and doing valve seats you might consider renewing the inlet valve guides, as the induction stroke tends to suck oil down the valve stems. Previously I have installed oil seals on the inlet valves by machining the top of the guides.
These days of exhaust gas measuring at MOT the oil seals save discussions regarding original levels of exhaust gas.

Dave the cog.

Oldtimer_Basis
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Re: Bubbles in the coolant tank, blown head gasket?

Post by Oldtimer_Basis »

I relpaced the Head-Gasket a few months ago and chose this Gary Kemp MLS Gasket. It is much more expensive than those normal "Cardboard-Gaskets", but it seems to be the better Optiion. I´m pretty sure, my Gasket has already been replaced some Time before by a standard one... and it was rotting away because of the Open-Deck-Design of the Block - so it started spitting out white Puffs of Smoke through the Exhaust. This cannot happen with a Steel-Gasket.

Pete Boole
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Re: Bubbles in the coolant tank, blown head gasket?

Post by Pete Boole »

Oldtimer - what torque settings did you use with the MLS gasket? Did you also use Gary Kemp's head studs?

Pete

Oldtimer_Basis
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Re: Bubbles in the coolant tank, blown head gasket?

Post by Oldtimer_Basis »

I simply went with the 75 lbs for the inner 6 and 70 lbs for the outer - same Torque as recommended for the normal Goertz (Goetze? Gruetze? :lol: whatever, you know what I mean). I used the stock Studs and Nuts. 3 Steps with 30 minutes Interval and after 24 h´s half a Turn back and retighten. The 24 h´s mode was recommended to avoid retightening the Nuts after the first 500 Kilometers, because that would really have been a hassle :?

HypnoToad
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Re: Bubbles in the coolant tank, blown head gasket?

Post by HypnoToad »

The CO2 tester finally arrived - After getting the engine up to temp it went yellow soon enough:

Image
Oldtimer_Basis wrote:
Sat Apr 30, 2022 16:53
I relpaced the Head-Gasket a few months ago and chose this Gary Kemp MLS Gasket.
Thanks, the MLS gasket that looks like the way to go. It sounds like it should last longer than the composite one, in theory at least. If so then it will be worth it as it takes quite a while to get to the head gasket.

I still havent managed to get the head off yet but the plan is to do this on the upcoming weekend. Thanks for the help and advice so far.

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