KAD300 - advice on supercharger rebuilds

F

frazion

Active Member
Joined
30 Aug 2020
Messages
58
Visit site
Hi folks, my port engine started overheating this year. While in the water, I've changed the impeller, flushed the raw water and internal coolant systems (oxalic acid flush), no joy, checked the temps with an ir gun and sure enough, its hot alright. Specifically the supercharger heats up so much faster than the SB charger. I drained the oil and its a horrible grey goo colour....not good...refilled, and now that the boat is out the water i checked the oil again with a drain and its still grey. I kinda expected that since i wasnt going to get all the old oil out in the first go...I'm also not sure why an overheating supercharger would make the engine overheat but its clearly an issue so one thing at a time. So, the compressor is removed, the heat exchanger is removed and im about to pressure test the heat exchanger. I figured i would remove the compressor sump, and check it out, ensure all the oil is cleaned out and see if there are any metal bits in there that indicate wear.

I'm aware these are stupid expensive so i'm thinking it would be an idea to send to a pro for a refurb, preferably one that does an assessment before just doing a rebuild! worst case, ill make a youtube of taking it apart cos i cant seem to find one!

Thats a long winded post but the question really is:

1) Anyone experienced dirty grey oil in the compressor before and what was it (im hating the idea but im thinking dodgy bearings and other unfun guff)
2) Recommendations and cost expectations for a compressor review and rebuild

ta fanks.
 
I'm no expert but from what I understand, a small amount of any old oil can give new oil a grey colour. So another oil change might be worth doing. Does the compressor sound and run OK?

Ref your overheating, have you tried to rebuild the sea water pump? These can be affected by worn cams, impeller covers, etc IIRC.

Also, and I'm not sure it's an issue on these engines, but are all the cooling pipes OK? Could one of them be collapsing which is restricting flow? Are there any other blockages in cooling system?

@volvopaul any thoughts?
 
Thanks for the response. The sea water pump was rebuilt recently and although i didnt change the cam, just the bearings and seals, the throughput is observably hefty with a nice cool feel on the now new faceplate of the raw water pump. no blockage in the strainer and all pipes are observably not collapsed. i also checked the exhaust elbow and although its rusty as expected, its not blocked. Theres plenty brown goop in the reservoir tank, this engine feeds the calorimeter so ill be running another oxalic rinse to try and reduce that build up again. ive just thought that i havent checked that the thermostats open at the right temps so will bring them home for a boil on the hob and an IR gun check (shhh dont tell the wife!). But....if i watch the temps on both engines started at the same time, the increase rate on the port from cold is noticeable faster that SB. so while ill check the thermostats anyway, theres still a more rapid increase in temps pre-thermo.

the compressor blows plenty but to my ears sounds a bit gritty when running. just looked at the o-ring price. £50 for a gasket....crazy.
 
Last edited:
Where the air pipe (approx 2" diameter black pipe) goes into the back of super charger did any of it leak air ? on my old boat it did see at the bottom of page 2 here

jon and michie

Thread 'Kad 300 lagging'

Hi - I have found this weekend that the engine would get to 2500rpm easily but would take a while to get to 2900rpm never mind any higher.
I opened the hatch whilst docked and started the engine and looked at the supercharger clutch which appears to be engaging.
But I did notice at the rear of the charger where a large black pipe goes in air appeared to be coming out.
Should the connection between the charger and the pipe be air tight?
If this is the cause of the "engine lag"
Is there some sort of seal kit that is easily available.
And is it an easy fix?

An opinions welcomed
Jon

mine was leaking air because of the sealant used by volvo had basically worn away.

This is my thinking / opinion - If its leaking then the chances are the turbo cant take over which in turn the supercharger could be working overtime which in turn equates to more heat
 
You must log in or register to reply here.

Share this page

Top