I have leaks on either side of the gas blocks or from the isolators or have HP/IP leaks into the CCR from the gas blocks or pipe work.


Check the 5 o-rings on the manual injection bar and replace as necessary. Note. There are 2 different size o-rings on the bar.

Ensure the correct o-rings are fitted in the correct positions. If no injection occurs when the manual injector button is depressed try backing off the button a little. On earlier Sentinel units if the button was screwed down too far there could be a flow restriction.

If leaks are noted around the off board connectors or the off board connector blank plugs then check the seal or o-ring for damage and replace as necessary. Note. Take care in refitting either the off board connector or blank plug as these metal fittings are screwed into the plastic gas block.

If leaks are noted around the 3 Miflex hoses entering the gas blocks they should be carefully removed and the o-rings checked. Note. Great care should be taken when removing and especially refitting theses hoses as the metal hose ends screw into the plastic gas block. With the Sentinel 2 wrenches should be used, the first to hold the insert still and the second to remove or refit the hose.

If leaks are noted around either ADV or Solenoid Isolator they should be removed and the o-rings checked and replaced as necessary.

If leaks are noted from any Miflex hose end remove the hose and check the o-rings.

If Miflex hoses have been removed ensure correct fitting location on reassembly by following the hose end colour coding. Note. If colour coding cable ties are missing re assemble using the download ‘Pipe work diagram’.

If leaks are noted from any of the metal pipe-work the Swagelok cone-fittings should be tightened slightly with 2 7/16ths wrenches. Note. Always check the condition of the first stage DIN o-rings.

Further Resources

Assembly & Testing Document

Video Link: Gas Block Manual Injector Stripdown
Video Link: Gas Block Manual Injector Assembly
Video Link: Gas Block Flow Stop Stripdown
Video Link: Gas Block Flow Stop Assembly