B737 MAX Technician reported during installation of the lavatory waste compartment fire extinguisher; they found the compartment not sealed properly.

Narrative

During accomplishment of job card XX-XXXX-X-XXX technicians noted that during installation of waste compartment fire bottle there was no sealant filling the gap between the probes on the fire bottle that extend into the was compartment and the structure. A review of the Aircraft Maintenance Manual (AMM) XX-XX-XX-XXX-XXX makes no mention of filling the holes with sealant after installation of the fire bottle however the Component Maintenance Manual (CMM) for the Lav A; D; E and T (XX-XX-XX; XX-XX-XX; XX-XX-XX and XX-XX-XX) it clearly calls out that after installation of the fire bottle apply RTV102 to fill the gap in the hole between the probes and the waste compartment structure.Suggestion: AMM XX-XX-XX-XXX-XXX needs to be revised to comply with the installation procedure of the Lavatory fire bottles which will then correct the task card through the program. An engineering authorization needs to be released to go out to the 737MAX fleet as well as the other fleet to verify that the fire containment area is not compromised due to the sealant not being installed. Aircraft X is only 2.5 years old and this is the first time the bottles have come out for weigh check so the sealant has been missing since the aircraft was built.