Is This Head Gasket Blown?

StuarT595 · Jan 19, 2021

Yorkshireman said: ↑

I’d say without. It won’t open unless with very hot water so you’d only get to flush as far as the stat in either direction and you don’t want to dislodge anything that could get stuck in it and cause a blockage. Even fully open when the engine is up to temperature it could be considered to be a restriction in the flow of the coolant and easily blocked.
Good work so far, best of luck with the repairs/rebuild.
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Makes perfect sense to leave it out after reading this...many thanks for that and the encouragement. Will put the thermostat housing back together using the old sealing ring for now then

StuarT595 · Jan 19, 2021

Adie P said: ↑

Morning Stuart. Sorry I missed this last night.

If the valve clearances had closed up completely then there's a very strong chance that that will be the cause or a major part of the poor running/starting issues.

In terms of backflushing, it will be worth your while removing the rad. and flushing it through via the outlet at the bottom - so the reverse direction to normal flow. If you're taking the water pump off then that will be cleaned up anyway so I'd guess an initial run with a cleaner descaler should be OK. I'm sure if that's not wise then someone with more experience will chime in on that.

I'd definitely consider having the head professionally cleaned though - the coolant is doing most of its work here so that's where the passageways need to be clear and open.

Good luck with it all.
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Re the valves, I’m definitely beginning to think they were the culprit to the rough running and poor starting, especially as the exhaust gasses have made it back to the air filter.
Thanks for the backflushing update...yes, I see now, and have already hosed the rad in both directions, but a good cleaner will still be needed I’m sure...I wonder about filling it with coke or similar, just to give it a head start?
I’m looking for a company in the Bristol/Glouc/Stroud area today to see what’s available re a head clean because I too feel it would be a good idea.
Cheers Adie...appreciate all your insights!

Adie P · Jan 19, 2021

StuarT595 said: ↑

Re the valves, I’m definitely beginning to think they were the culprit to the rough running and poor starting, especially as the exhaust gasses have made it back to the air filter.
Thanks for the backflushing update...yes, I see now, and have already hosed the rad in both directions, but a good cleaner will still be needed I’m sure...I wonder about filling it with coke or similar, just to give it a head start?
I’m looking for a company in the Bristol/Glouc/Stroud area today to see what’s available re a head clean because I too feel it would be a good idea.
Cheers Adie...appreciate all your insights!
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Pleasure!

Try these people for the head/test clean .... http://www.pricebrosengineering.co.uk/ That's just from a google search but worth a 'phone call.....

I think filling the rad with cheap cola and leaving it overnight, then flushing thoroughly is unlikely to do any harm .... unless it's on it last legs anyway - in which case it's better to find out now rather than at 100 miles away and 70 miles per hour?

Tricky-Dicky · Jan 19, 2021

A good way of getting the cooling system clean is to flush with a weak hydrochloric solution (alloy wheel cleaner) but if it's not terrible which yours isn't seen one hell of a lot worse by the looks of it just a flush with a strong detergent and hot water, another option is a caustic solution but if left it will eat alloy.
When flushing you want no obstructions so thermostat removed as said, as for the air filter smelling of fumes does the evap/breather system run back to the air box? (usually does) bad ring seal etc will result in the smell although this is likely to happen to a degree anyway due to the way the system works.

StuarT595 · Jan 19, 2021

Tricky-Dicky said: ↑

A good way of getting the cooling system clean is to flush with a weak hydrochloric solution (alloy wheel cleaner) but if it's not terrible which yours isn't seen one hell of a lot worse by the looks of it just a flush with a strong detergent and hot water, another option is a caustic solution but if left it will eat alloy.
When flushing you want no obstructions so thermostat removed as said, as for the air filter smelling of fumes does the evap/breather system run back to the air box? (usually does) bad ring seal etc will result in the smell although this is likely to happen to a degree anyway due to the way the system works.
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Really appreciate this, TD...I’ll definitely upgrade my understanding of the evap system.
There was a small amount of dark, sticky residue coating the inlet manifold, worse in the nearside manifold, which is what first made me think exhaust gases might be venting past the inlet valve? I guess I’ll know a little more when I remove the inlet valves today...hopefully it’ll be obvious if one or more of the valves have been bypassing?
Many thanks again...such a fantastic forum, so much Triumph knowledge in one location.

StuarT595 · Jan 19, 2021

Adie P said: ↑

Try these people for the head/test clean .... http://www.pricebrosengineering.co.uk/ That's just from a google search but worth a 'phone call.....
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Have taken a look...they look promising, will call them later...thanks so much

Yorkshireman · Jan 19, 2021

The breather/evap system will smell of old hot oil if it’s been doing it’s job right and could smell like exhaust.

StuarT595 · Jan 19, 2021

Yorkshireman said: ↑

The breather/evap system will smell of old hot oil if it’s been doing it’s job right and could smell like exhaust.
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Ah, OK...another piece in the puzzle...many thanks

Tricky-Dicky · Jan 19, 2021

StuarT595 said: ↑

Really appreciate this, TD...I’ll definitely upgrade my understanding of the evap system.
There was a small amount of dark, sticky residue coating the inlet manifold, worse in the nearside manifold, which is what first made me think exhaust gases might be venting past the inlet valve? I guess I’ll know a little more when I remove the inlet valves today...hopefully it’ll be obvious if one or more of the valves have been bypassing?
Many thanks again...such a fantastic forum, so much Triumph knowledge in one location.
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It would be very unlikely that the smell would be due to badly seating inlet valves due to the way the engine works...just an air pump I have seen it from bad valve timing and spitting back but I strongly suspect what your smelling is the result of engine breathing....you will usually get a bit of residue just from petrol vapour alone anyway.

StuarT595 · Jan 19, 2021

Tricky-Dicky said: ↑

It would be very unlikely that the smell would be due to badly seating inlet valves due to the way the engine works...just an air pump I have seen it from bad valve timing and spitting back but I strongly suspect what your smelling is the result of engine breathing....you will usually get a bit of residue just from petrol vapour alone anyway.
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Sounds like good news, I could be getting a little paranoid with this engine...it may even be a ‘good un,’ I just don’t know it yet!

speeder · Jan 25, 2021

StuarT595 said: ↑

Many thanks, Freck...top info., really good to know it isn’t always obvious.
I haven’t checked the head for warp yet...I’m going to borrow an engineers’ edge tomorrow at the garage (taking the car in for MOT so perfect timing).
I always thought OHC engines that run the camshafts in ‘shells’ cast into the head itself, couldn’t be skimmed? Good to know a couple of thou off has worked for you
Will definitely be pulling and resealing the liners, I’ve made a puller from 2 x 3” drain plugs...looking forward to trying it out.
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You can skim the head on OHC engines,it just means the entire head and cams are just a few thou' lower...this is easily taken up by the cam chain tensioner.
I've looked at the pictures but difficult to discern much.
I always get the components scrupulously clean first and then start inspecting them.
From what you say l suspect the tight valve clearances are a major factor in the rough running issues.

StuarT595 · Jan 25, 2021

M

speeder said: ↑

You can skim the head on OHC engines,it just means the entire head and cams are just a few thou' lower...this is easily taken up by the cam chain tensioner.
I've looked at the pictures but difficult to discern much.
I always get the components scrupulously clean first and then start inspecting them.
From what you say l suspect the tight valve clearances are a major factor in the rough running issues.
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Many thanks for taking a look, much appreciated. Luckily for me the head doesn’t even take a thou beneath an engineer’s straight edge, and doesn’t have any corrosion/imperfections. It’s currently with the engineers for a steam clean and pressure test
I don’t know where I read it, but I always thought the problem with skimming the head, where cam bearings were integral, was that the cams were left running in an arched head? I could’ve totally made that up, but it kind of makes sense? I’ve put an exaggerated picture of my possibly/likely flawed understanding below.

speeder · Jan 25, 2021

StuarT595 said: ↑

M

Many thanks for taking a look, much appreciated. Luckily for me the head doesn’t even take a thou beneath an engineer’s straight edge, and doesn’t have any corrosion/imperfections. It’s currently with the engineers for a steam clean and pressure test
I don’t know where I read it, but I always thought the problem with skimming the head, where cam bearings were integral, was that the cams were left running in an arched head? I could’ve totally made that up, but it kind of makes sense? I’ve put an exaggerated picture of my possibly/likely flawed understanding below.

View attachment 119213
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Yes, it's all a question of severity, anything more than a few thou and the head is probably scrap, when l used to do them we used to skim only the minimum to clean up and then check the cams still turn freely with caps bolted up.

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