No compression cylinders 1&2

[soilman]

Hi all, my car 803 1954 broke down last week, I was heavily loaded with camping gear off for the week went she started to make a rattling sound(sounded like a loose exhaust or something) and lost a substantial amount of power. Managed to make the last 2miles at the speed of 10mph.
I am a total novice, had the whole engine rebuilt 3 years ago at a eye watering cost.So I have decided that I will carry future repairs myself hence seeking help.
So far I have taken of the rocker and checked the valves etc and all look good including gaps and movement.Theres no excessive smoke or mayonnaise.I carried a compression test and found the following

No 1 32 dry 70 wet
No 2 36 dry 70 wet
No 3 105 dry 120 wet
No 4 105 dry 115 wet

Doesn’t look good?

Judging by this I suspect I need to remove the head to check gasket, valves, and rings?

Any comments ideas much appreciated

[myoldjalopy]

Does sound as if the head gasket may have gone between 1 and 2. May as well lift the head for a look.

[simmitc]

Classic head gasket failure. Follow the procedure in the manual to remove and refit the head with a new gasket. Whilst the head is off, check that there has been no damage to the mating surfaces of either head or block. Unfortunately, after three years, the warranty will be expired. There shopuld be no need to worry about valves and rings; but you'll know as soon as you lift the head.

[oliver90owner]

Do check the head with a straight edge for flatness, if the gasket has failed. The gasket will likely fail again if the head is warped....

[soilman]

Hi, I have taken off the head and yes its the gasket, SEE ATTATCHED PHOTOS.

The valves etc all look ok to me, but I haven't a experienced eye, any comments welcome. I plan to check with a engineering straight edge and feelers, after cleaning the head up, and then reassemble.

Should I try to clean the carbon off of the valves etc, any suggestions on the best method???

best regards Bruce

Note is there a torque for the bolts for the rocker assembly?

[Nickol]

Do check in you tube for decarbonising methods and what tools to use. I like the green scourer method myself together with WD40 (it is about all its good for!)

[philthehill]

There is a torque setting for the rocker shaft pedestal bolts - 25lbf ft.

All the torque settings are listed at the start of the technical mechanical section under threads.

[soilman]

ok thanks, when should they be torqued before or after the main bolts to the head?

[philthehill]

Nip the pedestal bolts up but torque the rocker pedestal studs after torqueing the main head studs.

[pgp001]

Is it possible to obtain a different head gasket with smaller main holes for the 803cc ?

There is a lot of wasted area where a gasket could fit and not have the very thin sections between the bores.
It will also reduce the compression ratio having that annular space between the head and block.

I think I would consider making my own from copper sheet, I did that on my Austin 7 engine when I tuned it and never had any problems.

Phil P

[philthehill]

Here is a head gasket suitable for the 803cc engine.

https://www.minispares.com/product/Clas ... o%20search

Unfortunately out of stock at the moment.

or

https://www.minispares.com/product/Clas ... |Back%20to

The annular space will have very little effect on the compression ratio as the volume created by the thickness of the head gasket is about 2.5cc in total.

See also the latest Minor Matters re head gasket which can be found in the 'view point' section.

Here is a NOS 803cc head gasket:-

https://www.ebay.co.uk/itm/Morris-Minor ... xy1klRZ6p1

[soilman]

hi, so checked and clean head all good, coming to the block would you suggest removing the studs to get better access to cleaning, and does that also need checking for tolerance?

[philthehill]

The top of the block should be cleaned and checked for trueness.
It is best if the studs are all removed and the stud holes countersunk to remove any pull up of the top of the block. This does help in seating the head gasket.

img178.jpg (446.04 KiB) Viewed 1164 times

[soilman]

Thanks Phil, much appreciated, so just hand held drill lightly pressed into hole? Also what's the best way to remove studs two nut method or should I buy a tool do you think? and are the studs torqued??

regards Bruce

[philthehill]

Just use the two nut locked together way of removing the studs.
A hand drill with a 1/2" or 13mm drill bit lightly pressed into the block is just right. Use a vacuum cleaner to ensure that any swarf is removed as you drill.
The studs should be nipped up just past finger tight.
For those studs fitted into holes that enter the water jacket - I would recommend that you use Loctite 243 'Lock & seal' so as to ensure that coolant does not weep past the threads.
The head nuts are torqued up dry - so no lubricant is required on the UNF threads.
No lubricant either on the UNC threads.
Good luck
Phil

[soilman]

Hi my car is all back together and running, so satisfying, never done anything like this before, many thanks for advice and encouragement
Bruce