cyl head pressure
-
FBJ
- Posts: 667
- Joined: Wed Nov 10, 2010 7:31 pm
- Location: peterborough
- Has thanked: 5 times
- Been thanked: 31 times
Re: cyl head pressure
Johnr the crack in the head is quite common on these motors apparently. When flos gets hot it smokes more. Not when cruising on a motorway.. when you pull up an idle
-
uber pikey
Re: cyl head pressure
There is only one way to check if the head is water tight(pressure check) and that's with a big enough bucket and lots of rubber expandable bungs to fill the holes then attach a hose and pressurise it and wait to see what happens, this doesn't elimenate other issues with the head.
if a vehicle smokes on start up it's generaly the valve stem seals as oil will seep past and lie on the pistons untill started.
A crack in the head might show an increase in oil or water pressure but the only way to check is to strip it realy. It might be worth removing the breather pipe to see if there is excess oil being blown though, this might elimenate rings as the pressure from the barrel has to go somewhere.
Low compression could also be down to valve seat as mentioned earlier, this might be picked up on a carb balance as a fluctuation in pressure like that could show up quite well but would only elimenate the intake valve.
Valve gaps are also a consideration as you might have one stuck open all the time if they have too small or no gap at all.
Hope this helps.
Good luck.
if a vehicle smokes on start up it's generaly the valve stem seals as oil will seep past and lie on the pistons untill started.
A crack in the head might show an increase in oil or water pressure but the only way to check is to strip it realy. It might be worth removing the breather pipe to see if there is excess oil being blown though, this might elimenate rings as the pressure from the barrel has to go somewhere.
Low compression could also be down to valve seat as mentioned earlier, this might be picked up on a carb balance as a fluctuation in pressure like that could show up quite well but would only elimenate the intake valve.
Valve gaps are also a consideration as you might have one stuck open all the time if they have too small or no gap at all.
Hope this helps.
Good luck.
-
johnr
- Club Member
- Posts: 3022
- Joined: Sun Oct 24, 2010 9:58 pm
- Location: lancashire
- Has thanked: 234 times
- Been thanked: 342 times
Re: cyl head pressure
yes i know, a couple of my spare heads have cracks from the plug thread.FBJ wrote:Johnr the crack in the head is quite common on these motors apparently. When flos gets hot it smokes more. Not when cruising on a motorway.. when you pull up an idle
-
Pedda
- Club Member
- Posts: 1516
- Joined: Mon Oct 25, 2010 11:21 am
- Location: Stadtlohn, Germany
- Has thanked: 53 times
- Been thanked: 198 times
Re: cyl head pressure
...and they don't effect the engine's function. Let alone make it smoke or sip oil.
If a wet compression test gives much better results than dry it's down to rings/ bore, as stated above. It smoking from start or accellerating from idle it's stem seals. Once you have the cyl head down it's always a good idea to lap the valve seats.
If a wet compression test gives much better results than dry it's down to rings/ bore, as stated above. It smoking from start or accellerating from idle it's stem seals. Once you have the cyl head down it's always a good idea to lap the valve seats.
