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Hi all, I’m planning for a complete coolant flush in my 91 (L98) and replacing the hoses, and would like your advise/feedback on the following:
1- The car is on jackstands (all four sides), should I keep it or only the front should be raised for the flush?
2- Can I do the flushing without removing the knock sensor? Or it must come off?
3- The heater core is deleted, I by passed it due to a leak (PITA to replace it). Will that be a problem to flush and replace the coolant without the heater core?
4- If anyone can share the complete flushing procedures (steps) that would be appreciated.
5- How to know if the system needs burping and how to burp it?
if anything else is missing pls advise..,
appreciate the help.
TIA
not sure how much of this is relevant for yours as mine is an '85 - i believe the strong recommendation is for the knock sensors to come out - when i did mine last year i did not remove them - but i also knew i may be doing it a second time and would at that point (since then i have however had the heater core replaced) at the time i did it - the heater core was bypassed and it worked fine.
i cleaned the thermostat - it tested fine so i reused
i know there are more details and more who may have more specifics but hopefully this helps a little - also remember to clean in front of the radiator - miracle worker for keeping things cool
I found that just removing the knocks and letting the coolant slowly drain out got very little of the sediment in the lower part of the block. What you need is vigorish movement of the coolant in the lower block not just gravity draining. My shop vac flush really worked for me after two attempts at regular draining. Now after two years no brown sludge. My 96 is a little different than your setup but you can adapt. Dan
sorry Whaleman forgot about that - yes that was something i tried on Whaleman's recommendation - did get things moving - i have a small dewalt battery leaf blower and the rubber tip fit very well
Zerovette7 - First off - not having a heater core hooked up really doesn't matter - (I'm assuming the two heater hoses that feed / return from the heater core are just connected to each other.)
Now - as for removing the knock sensors / block drain plugs. Most people have never taken them out - and I firmly believe most cars go to the junkyard with those plugs in place just the way the factory left them. BUT - as someone who has removed knock sensors from a couple of C4's - I would recommend doing it. It's a not a fun job - but it doesn't rise to the real PITA stage (just expect to get coolant all over the place - including on yourself).
IMO - there is not very good circulation down in the lower part of the block - and the stuff that gets down there - doesn't really move around very much - so while you will almost certainly get some crud out - failing to do it is not hyper critical, but I would say to do it once, and get that junk out of the engine. (Note - It's not crazy that some people will get nothing out when they pull the drain plugs / knock sensors - due to the fact that so much crud has accumulated over the years - it has formed a nearly solid plug, - sometimes a small screwdriver or a punch needs to be tapped into the open drain plug hole to get stuff to actually drain out.
I like the shop vac way! I have an air blower that I can use … will give it a try before removing the knock sensors..
so once all coolant blown out of the block, I fill again with tap water or distilled water? And repeat again…until clear water is out?
then I close everything and put back all the hoses and fill the coolant till the upper surge tank is full and overflow bottle is filled to cold line… is that right?
then switch on the car and idle it until operating temp is reached and thermostat opens up and watch the upper surge tank and add coolant as needed? And we are done .. correct?!
Need an advise,
when i removed the thermostat the below photos of a switch or connector was connected with the bolt holding the water neck (thermostats housing) looks like the electrical connectors are corroded and snapped when removed,…
I guess it is for the injectors and vacuum lines (correct me if I’m wrong) how this can be fixed or replaced.. any part number so as to orders a replacement?
Zerovette7 - First off - not having a heater core hooked up really doesn't matter - (I'm assuming the two heater hoses that feed / return from the heater core are just connected to each other.)
Now - as for removing the knock sensors / block drain plugs. Most people have never taken them out - and I firmly believe most cars go to the junkyard with those plugs in place just the way the factory left them. BUT - as someone who has removed knock sensors from a couple of C4's - I would recommend doing it. It's a not a fun job - but it doesn't rise to the real PITA stage (just expect to get coolant all over the place - including on yourself).
IMO - there is not very good circulation down in the lower part of the block - and the stuff that gets down there - doesn't really move around very much - so while you will almost certainly get some crud out - failing to do it is not hyper critical, but I would say to do it once, and get that junk out of the engine. (Note - It's not crazy that some people will get nothing out when they pull the drain plugs / knock sensors - due to the fact that so much crud has accumulated over the years - it has formed a nearly solid plug, - sometimes a small screwdriver or a punch needs to be tapped into the open drain plug hole to get stuff to actually drain out.
You are correct Purple about the lack of vigorish movement in the lower block. The problem I had was I drained out the suspended crud the first two times I flushed and pulled the knocks and everything was beautiful for maybe 1000 miles and the suspended crud came back. After using the shop vac and agitating the crud down there maybe 25 times it has now stayed clean. Dan
Coolant Flush Advise..
