Head Gasket Failure?
- Tom Brearley
- Posts: 120
- Joined: Sun Apr 01, 2018 6:54 pm
- Forename: Tom
- Surname: Brearley
- MGCC Member: Yes
- Location: Devon
Head Gasket Failure?
Hi,
Having worked reliably for almost 11 whole months, my GT has decided it's unhappy again.
Accelerating up a gentle hill in overdrive, a loud & rapid 'clacking' started coming from the engine. Power and drivability reduced. Accelerating produced severe engine shake. The clacking varied according to engine speed.
A compression test shows that cylinders 3 and 4 have 50psi (while 1 and 2 are around 170psi which is normal). When testing cylinders 3 and 4, there's an audible 'chuffing'.
There's no 'mayonnaise' on the radiator cap or oil-filler cap. There's no white smoke from the exhaust and the coolant level hasn't dropped.
But am I right in thinking this is probably head-gasket failure?
Thanks
Tom
Having worked reliably for almost 11 whole months, my GT has decided it's unhappy again.
Accelerating up a gentle hill in overdrive, a loud & rapid 'clacking' started coming from the engine. Power and drivability reduced. Accelerating produced severe engine shake. The clacking varied according to engine speed.
A compression test shows that cylinders 3 and 4 have 50psi (while 1 and 2 are around 170psi which is normal). When testing cylinders 3 and 4, there's an audible 'chuffing'.
There's no 'mayonnaise' on the radiator cap or oil-filler cap. There's no white smoke from the exhaust and the coolant level hasn't dropped.
But am I right in thinking this is probably head-gasket failure?
Thanks
Tom
1973 MGB GT
Mallard Green / Autumn Leaf
Mallard Green / Autumn Leaf
Re: Head Gasket Failure?
Don't know, never having experienced HGF myself. But have you had the rocker box cover off to see if anything is amiss in there?
Mike
1969 MGB GTV8 3.9 Conversion. Many classics have passed through my hands but the faithful BGT V8 is the last man standing.
1969 MGB GTV8 3.9 Conversion. Many classics have passed through my hands but the faithful BGT V8 is the last man standing.
- Tom Brearley
- Posts: 120
- Joined: Sun Apr 01, 2018 6:54 pm
- Forename: Tom
- Surname: Brearley
- MGCC Member: Yes
- Location: Devon
-
- Posts: 207
- Joined: Fri Sep 28, 2018 4:55 pm
- Forename: Dave
- Surname: Wheatley
- Location: SW Scotland
Re: Head Gasket Failure?
99% certainty of head gasket failure in my opinion.
1978 MGB GT
1967 Morris Minor convertible
1972 Ford Cortina
2000 Mercedese Benz SLK 230K
No modern!
1967 Morris Minor convertible
1972 Ford Cortina
2000 Mercedese Benz SLK 230K
No modern!
Re: Head Gasket Failure?
I think you will find that you have a piece of head gasket missing between 3 and 4 cylinders. If you drive it like this you risk eroding the head and block in that location necessitating skimming of both. A common issue with A series and B series engines.
Usually caused by surfaces not being perfectly flat, head bolts not tight enough or overheating - usually cylinder 3.
Ian F
Usually caused by surfaces not being perfectly flat, head bolts not tight enough or overheating - usually cylinder 3.
Ian F
MGCC member
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
- Tom Brearley
- Posts: 120
- Joined: Sun Apr 01, 2018 6:54 pm
- Forename: Tom
- Surname: Brearley
- MGCC Member: Yes
- Location: Devon
Re: Head Gasket Failure?
"If you drive it like this you risk eroding the head and block in that location necessitating skimming of both."
Annoyingly, I drove it for 35 miles to get home - having been advised it was a cracked exhaust manifold.
Annoyingly, I drove it for 35 miles to get home - having been advised it was a cracked exhaust manifold.
1973 MGB GT
Mallard Green / Autumn Leaf
Mallard Green / Autumn Leaf
Re: Head Gasket Failure?
It may be OK, you just need to look. There will be burn marks across that area, but check with a straight edge and feeler gauges. It may always be a weak spot though if you don't get the surfaces refaced
Ian F
Ian F
MGCC member
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
- Tom Brearley
- Posts: 120
- Joined: Sun Apr 01, 2018 6:54 pm
- Forename: Tom
- Surname: Brearley
- MGCC Member: Yes
- Location: Devon
Re: Head Gasket Failure?
Thanks All.
If anyone can recommend a classic-friendly garage in the Exeter area, I would be grateful. The one I have used before (at Tipton St John) can't book me in until late September - and I'm not that keen to do the job myself.
If anyone can recommend a classic-friendly garage in the Exeter area, I would be grateful. The one I have used before (at Tipton St John) can't book me in until late September - and I'm not that keen to do the job myself.
1973 MGB GT
Mallard Green / Autumn Leaf
Mallard Green / Autumn Leaf
-
- Posts: 238
- Joined: Tue Sep 22, 2020 9:33 am
- Forename: Chris
- Surname: S
- Location: UK
Re: Head Gasket Failure?
It is very easy to get the head off a B series engine with basic tools, nothing to be wary of. Take the head into any engine engineering workshop to have it checked. Leave instructions for them to skim it if needed and if so to advise you whether the level of damage would necessitate skimming the block (generally less likely to be needed). Order a new head gasket of a known make. Reassembly is the reversal of dismantling, ensure you have a feeler gauge and a spare hour to adjust the tappets. Enjoy driving it again.
1979 MGB GT
2003 MG TF
2003 MG TF
-
- Posts: 787
- Joined: Wed Dec 21, 2016 6:07 pm
- Forename: Vic
- Surname: Butler
- MGCC Member: Yes
- MGOC Member: Yes
- Location: North West Hampshire
Re: Head Gasket Failure?
The best gasket is a Payen.
1977 Stage 2 MGB GT
1975 SWB Series 3 Land Rover with a later 2.5 petrol engine
1975 SWB Series 3 Land Rover with a later 2.5 petrol engine