g741.org

M37UK wrote:I decided to run a compression test today and here are my findings, from cylinder 1 to 6:

110 psi
112 psi
101 psi
110 psi
102 psi
119 psi

Seems to be a quite a variation between the lowest and highest, should I be worried unduly ??
I have noticed a fair amount of "ticking" noises coming from the valve side of the engine, if this is related.

Charles, if you are out there, could you cast your eye over these results please ?

Cheers
Stu

MSeriesRebuild wrote:

M37UK wrote:I decided to run a compression test today and here are my findings, from cylinder 1 to 6:

110 psi
112 psi
101 psi
110 psi
102 psi
119 psi

Seems to be a quite a variation between the lowest and highest, should I be worried unduly ??
I have noticed a fair amount of "ticking" noises coming from the valve side of the engine, if this is related.

Charles, if you are out there, could you cast your eye over these results please ?

Cheers
Stu

Cylinders 3 & 5 are on the low side. Pump about 3 good pumps from a pump oil can into the plug holes and retest immediately. If the pressure goes up significantly, rings and cylinder wall wear is the bigger issue. If this is the case, a rebuild only will fix that. If pressure changes little to none after adding the oil, valves are the issue. Grinding and reseating should likely fix that. The other readings are typical of a worn engine. 100 PSI is actually the border line where you will start to notice performance deteriorating a little at a time. 90 is to the point you will have intermittent skipping going on at best, below 90, well that's pretty much hopeless, appropriate attention required. Have you noticed anything that I've mentioned going on? If a retest shows valves are the likely cause, repair in that area should buy you a good many miles before it demands a rebuild. It won't be a powerhouse, and depends on how you need to use the truck.

M37UK wrote:

MSeriesRebuild wrote:

M37UK wrote:I decided to run a compression test today and here are my findings, from cylinder 1 to 6:

110 psi
112 psi
101 psi
110 psi
102 psi
119 psi

Seems to be a quite a variation between the lowest and highest, should I be worried unduly ??
I have noticed a fair amount of "ticking" noises coming from the valve side of the engine, if this is related.

Charles, if you are out there, could you cast your eye over these results please ?

Cheers
Stu

Cylinders 3 & 5 are on the low side. Pump about 3 good pumps from a pump oil can into the plug holes and retest immediately. If the pressure goes up significantly, rings and cylinder wall wear is the bigger issue. If this is the case, a rebuild only will fix that. If pressure changes little to none after adding the oil, valves are the issue. Grinding and reseating should likely fix that. The other readings are typical of a worn engine. 100 PSI is actually the border line where you will start to notice performance deteriorating a little at a time. 90 is to the point you will have intermittent skipping going on at best, below 90, well that's pretty much hopeless, appropriate attention required. Have you noticed anything that I've mentioned going on? If a retest shows valves are the likely cause, repair in that area should buy you a good many miles before it demands a rebuild. It won't be a powerhouse, and depends on how you need to use the truck.

I poured in a little engine oil into the plug holes and re-tested, readings went upto 130 psi which point towards rings and cylinder wall issues. I aint in the mood for rebuilding the engine so will have to live with it.
I havent had any performance issues with the truck at all apart from bad idling but she will sit at 50 all day on tarmac.
Once I install the electronic ignition and give the carb a service that should keep me going long enough to save for a 4BT.

Thanks for your advice Charles


Stu

M37UK wrote:Well, I decided to lubricate the o-ring on the compression tester in case it wasnt getting a good seal on the plug hole and redid the test .
This was about 12 hours after pouring some oil in the cylinder test.

118 psi
120 psi
115 psi
120 psi
115 psi
122 psi

I would say a better result?

Stu

MSeriesRebuild wrote:

M37UK wrote:Well, I decided to lubricate the o-ring on the compression tester in case it wasnt getting a good seal on the plug hole and redid the test .
This was about 12 hours after pouring some oil in the cylinder test.

118 psi
120 psi
115 psi
120 psi
115 psi
122 psi

I would say a better result?

Stu

M37UK wrote:Thanks Charles

What would the ticking noise most likely be caused by , tappets ??

Stu

cuz wrote:I've heard ticking from fuel pump arms on several makes. Willys is another.

As for the lifter ticking the lifters are available in oversizes to close that gap.