Leaking intake valve

[horsefly76]

 I was doing an inspection on the 6/1  Have the intake and exhaust off and noticed a fair amount of air leaking past the intake valve when rolled over to compression.

Exhaust was leaking also but not as bad.

I'm thinking pull the head and send it in for a good valve job.

Ehhhh just an excuse to hear some stories from you guys

[oliver90owner]

horsefly76,

First (might sound like a stupid suggestion) have you got valve clearance?

Second, and I expect this is the case, your valves are not seating properly (see below for reasons).

Third, send it in for a good valve job.  WHAT?!! You have done most of the work already and will finish the job when you replace the head.  YOU can do a good job in most instances.

Remove the head and find out why it/they is/are leaking.  It may be carbon on the valve stem, it may need lapping in with grinding paste.  It may be that the valve seats are not concentric with the valves.  It may be a cracked valve head, it might just be a scrap head.  Beware that valves have not been swapped inlet to outlet as they are not interchangeable without reseating them, even if they are the same material and dimensions.  Valve guides might be a problem too.  Until you know what is wrong, you won't know how expensive the fix is.  It could just be a couple of quid for some grinding paste (which will last you for the next 50 years, for this engine)

These engines are pretty simple and most jobs can be done in-house.  Only if it needs specialist machining would I ever send one out.  Get some engineer's blue and learn how to use it and do the job yourself if possible.  You don't even need engineer's blue - you can use a felt tip pen these days.

Find out why and then fix it.

Regards, RAB

[Reno Speedster]

When my Ashwamegh showed up the valves guides were very loose (you could rattle them from side to side) and the valves poorly fitted.  I had the head decked, bronze valve guides installed and the valves fitted for a woping $50 at my local machine shop.  Can you do it yourself? Sure, but for some jobs its worth just having it done.  While you are at it, have them magnaflux your head to make sure that it is OK.

[horsefly76]

horsefly76,

First (might sound like a stupid suggestion) have you got valve clearance?

Second, and I expect this is the case, your valves are not seating properly (see below for reasons).

Third, send it in for a good valve job.  WHAT?!! You have done most of the work already and will finish the job when you replace the head.  YOU can do a good job in most instances.

Remove the head and find out why it/they is/are leaking.  It may be carbon on the valve stem, it may need lapping in with grinding paste.  It may be that the valve seats are not concentric with the valves.  It may be a cracked valve head, it might just be a scrap head.  Beware that valves have not been swapped inlet to outlet as they are not interchangeable without reseating them, even if they are the same material and dimensions.  Valve guides might be a problem too.  Until you know what is wrong, you won't know how expensive the fix is.  It could just be a couple of quid for some grinding paste (which will last you for the next 50 years, for this engine)

These engines are pretty simple and most jobs can be done in-house.  Only if it needs specialist machining would I ever send one out.  Get some engineer's blue and learn how to use it and do the job yourself if possible.  You don't even need engineer's blue - you can use a felt tip pen these days.

Find out why and then fix it.

Regards, RAB

Right now I have no place to work on the engine we are in an 2 bedroom apartment till I we find a house. The engine is in a storage shed  That's why I'm thinking of sending the head in to a shop.

Valve lash is good it was first thing I checked. I think I may have to throw a set  of guides in as my engine likes to draw a lot of oil past the guide and slobber all over the place.

I know what I need to do, I have been working on aircraft piston and turbine engines from the age of 19 when I finished tech school. And now due to lay-off's  diesel generators for a rental company.

I wanted to know what problems other people had.

   

[horsefly76]

When my Ashwamegh showed up the valves guides were very loose (you could rattle them from side to side) and the valves poorly fitted.  I had the head decked, bronze valve guides installed and the valves fitted for a woping $50 at my local machine shop.  Can you do it yourself? Sure, but for some jobs its worth just having it done.  While you are at it, have them magnaflux your head to make sure that it is OK.

 Reno how much did you have taken off the head?

 My favorite part of an engine over haul was cleaning up the ports and taking a little off the head to wake it up a little.

[oliver90owner]

horsefly76,

My favorite part of an engine over haul was cleaning up the ports and taking a little off the head to wake it up a little.

That might be apropriate for a petrol engine but a 6 HP diesel?  As you have pointed out you are fully at home with these engines so you just need to think why they have the valves recessed and why they have shim gaskets under the cylinder block?     

You only take enough off to clean/true things up.  Or else in the future you may need it skimmed and it might be scrap instead.

I wanted to know what problems other people had.

Why didn't you just ask?   Some of us are not mind readers and/or simply answer the question for the benefit of any one else who might have a similar problem and is reading your thread for some useful information.

The engine is in a storage shed  That's why I'm thinking of sending the head in to a shop.

How much space do you need?  Make a board to fit over the head/block studs and then you will have a platform on which to work.  You can lay the head upside down over the studs and it will not fall on your toes!

Do I mind read here that you have never run your engine yet?  Or was it moved to storage recently?  Just asking.

Regards, RAB

[Reno Speedster]

 Reno how much did you have taken off the head?

 My favorite part of an engine over haul was cleaning up the ports and taking a little off the head to wake it up a little.

As little as possible.  I just had them clean it up and make sure that it was flat.

[horsefly76]

Do I mind read here that you have never run your engine yet?  Or was it moved to storage recently?  Just asking.
 
Regards, RAB

RAB

 Engine has been run but the house we lived in was a rental that had to go so engine was just moved into storage till we find a house to buy.

 It's about 105-110 deg here this time of year in Arizona so working in a hot shed after an 10-11 hr day at work (outside most of the time) is no fun.

 When I get some time off from work/wife/8 yr old I will pull the head and have it cleaned up if need be. I do plan on cleaning up some of the rough casting in the ports, nothing major.
 

[blacksea7]

Excellent posts, Gents!

Valve clearance a biggie... lose guides, carbon on the valve face, recessed valves (not good), cutting the head (not good)... You know, I'm here with a bunch of tinkerers! Kudos! I couldn't leave anything alone either... must be why my museum of engines still run as they did when they were manufactured... hey, was fun!

For what it's worth, most valve issues come from bad cams.. no heat treat, bad grinds, etc, soft tappets, improperly ground tappets, poorly adjusted valve clearances, poor materials or overheating... the latter of which creates the least issues.

If it's a depressed valve issue, buy a couple of new valves and have the head machined for an inserts and bring the valves back down where they belong. Compression and swirl are why the engines work... a depressed valve creates turbulence issues... cutting the head creates even more issues to contend with.

BTW, before I forget, Lister had (and still has) a natorious habit of placing the bore of the tappet off to one side of the cam. The reason being: By incorporating the offset tappet guide bore, the tappet was more so forced to spin thereby allowing great wear characteristics.

Gotta love the issues, creativity and BS...

We live in Arizona as well... in as much as it's hot here, the original Listers were developed to tolerate 125F temps while pulling continous rated power.  If you have radiator issues, try using drum cooling... works great!