should i flush the cooling system? ... V. new radiator

[affende]

opinions? 93 E34 with 220K and unreliable history

Radiator tank split at the crimp ... so im doing a cooling circuit service with new rad, hoses, mounts, fan shroud, t stat and housing (water pump is only 3 months old).

While im in there, should i run some cleaner through the system and flush it? This car has quite a few problems (tranny is questionable, engine eats oil, computer output on the dash is confused and just scrolls random symbols, needs thrust arms ... again, rear suspension is original with 220K miles and according to the BMW shop is bent and should be replaced)and im wanting to replace it ... my worry is that instead of making the system more efficient i will cause leaks by getting rid of the crap that is probably holding the system together or flush crap into the system (that was once solidly clinging to the block etc) that will clog small passageways (rad tubes, heater core).

am i overthinking or do i have valid concerns?

[ross1]

Sometimes the cleaner will reveal other weak spots, be prepared for more leaks after. Given the condition described I'd slap in the radiator, get enough coolant in there for freeze protection and call it a day. Gotta pick your battles.

[e34Croak]

I would definitely flush the entire system. Start fresh.

[affende]

I would definitely flush the entire system. Start fresh.

My OCD side agrees with you.


Sometimes the cleaner will reveal other weak spots, be prepared for more leaks after. Given the condition described I'd slap in the radiator, get enough coolant in there for freeze protection and call it a day. Gotta pick your battles.

My logical financially-sensitive side agrees with you.


1-1 TIE ... this is my life in a jar.

[kalevera]

I wouldn't bother flushing the system

Drain the block (both sides if it's a V8) and replace the radiator, call it a day

[SW530]

I wouldn't bother flushing the system

Drain the block (both sides if it's a V8) and replace the radiator, call it a day
+1

I wouldn't even drain the block, too much risk of stripping plugs. Just jack up the rear end 12-14" and almost all of what's n the block will come out the bottom hose. Besides, assuming you already flushed and added new coolant when you changed the water pump.. if so I wouldn't even drain it.. just change the radiator and hoses and leave it there.

[affende]

Didnt flush. 2 1/2 hours ... first time. I think i could cut that time in half now that i now what im doing. crimped off the lower hose (out of the bottom of the reservoir , no idea what it is) to keep as much in the system as possible.

New Radiator, upper and lower hose, mounts, t stat housing, t stat (associated gasket and o ring obviously). While i had the car on jacks i did the center exhaust rings as they had broken and we causing the MOST ANNOYING NOISE i have ever heard ... and thats saying something because i have a 4 year old that will not go more than 5 seconds without making completely nonsensical and meaningless noises.

Bleeding was easy as always ... no idea why there are horror stories with bleeding.

[maigo]

OP, did you raise the rear of car as suggested or keep it level?


Thx

[affende]

i had the front on ramps with the rear on the ground. I did this for a few reasons.

1) elevating the front of the system might make the bleeding process a little easier (i have always done it this way and bleeding has always been very easy)
2) my back likes things to be elevated to a comfortable working height
3) make the bleeding process easier
4) This helps drain the front of the system (which i was changing) while keeping as much coolant in the rear of the system as possible.
5) ease the bleeding process
6) im lazy with this car now. It has outlived its usefulness for me but with an impending crosscountry move, a family, a custody battle, and a recent job change i am not in a position to change vehicles / upgrade.
7) easy bleeding

- - - Updated - - -

and an update:

i have put almost 50 miles on the car between last night and this morning (weekends with the family = driving pointless around town in an effort to, what i can only assume, waste gas and further stress our finances).

There is very little change whatsoever in the cooling system other than an astounding lack of coolant outside said system. This affords me a few assumptions:

1) the original system was working at an acceptable rate ... other than the cracked radiator.
2) the new system is working at an acceptable rate as well.

sometimes no change in performance is a good thing.

I have noticed the car tends run just a tad cooler while stopped / idling. I attribute this to a new radiator without buildup and without clogged cooling fins. (i also sprayed out the transmission cooler and AC condenser with purple power and a hose to flush some junk out of the cooling fins of those ... a little added air flow can help a lot.

One problem i did notice was the lower crossmember / rad support (under the radiator) was gunked up with some form of oil and all kinds of road trash. I tracked this down to the loose bolt holding the transmission lines to the transmission cooler allowing ATF to leak out out of the cooler.

I just did a service on the transmission this summer with a flush, gaskets, and filters with Royal Purple (im addicted to this stuff for long term fluids) so im going to check the fluid level again although i have not noticed any new transmission problems so either:

1)the leak was negligible (which would be surprising as the bolt on the cooler was almost completely out)
or
2) the transmission cooling system went without fluid long enough that the pump burned up which actually saved the transmission by keeping fluid in instead of pumping it all out.

With that said, i have no idea about the internals of the transmission or its cooling system and this is just blind speculation. I have no idea how that connection would keep any fluid in the system with any kind of pressure. Im slightly familiar with pumps and closed systems in other applications ... and that connection was loose enough to spew all its fluid in short order.

[SW530]

I have noticed the car tends run just a tad cooler while stopped / idling. .

There really shouldn't be any movement of the temp gauge if everything is working as it should. The mid-setting (like a half needle shy of halfway) is really a wide margin of temps. I'm not sure what it is exactly, but it's wide. Otherwise our gauges would go up and down all the time like a real temp gauge does.. which would freak out most people. So they put "normal" to mean like a 25-30 degree wide margin. So if you're needle is moving cooler/hotter during normal use.. the temps are exceeding that wide margin and they really shouldn't. Considering all you've mentioned done already.. I'd look at the fan clutch and electric fan operation.. either of those has the potential to cause significant issues.

[5Toes]

+1

I wouldn't even drain the block, too much risk of stripping plugs. Just jack up the rear end 12-14" and almost all of what's n the block will come out the bottom hose. Besides, assuming you already flushed and added new coolant when you changed the water pump.. if so I wouldn't even drain it.. just change the radiator and hoses and leave it there.

stripping the plug??? its a steel bolt in the cast iron block dude... I would not be worried about that at all

OP - just make sure you use a new crush gasket or atleast sand your old one for reuse

[ross1]

stripping the plug??? its a steel bolt in the cast iron block dude... I would not be worried about that at all

OP - just make sure you use a new crush gasket or atleast sand your old one for reuse
I don't think concern is for the threads, rather the bolt head. These can be mighty stuck after twenty years, this combined with limited access for a good bite from the wrench and you need to be very careful.

[E38740iMD]

a bit off topic but you can flush the block of coolant? i didnt know this. can the m30 do this?

[5Toes]

Make sure you use the "box" end of the wrench or a socket... with a swivel handle ratchet plenty of access under the exhaust manifolds

[affende]

Make sure you use the "box" end of the wrench or a socket... with a swivel handle ratchet plenty of access under the exhaust manifolds

I had great access to not bother with it.

[SW530]

stripping the plug??? its a steel bolt in the cast iron block dude... I would not be worried about that at all

OP - just make sure you use a new crush gasket or atleast sand your old one for reuse

I'm getting too used to aluminum, didn't realize his was steel. Still, the bolt head could be easily rounded off. If going this route soak it first, use a tight wrench, and be careful.. It took me several days of soaking, careful easing, back and forth on my tranny drain plug.. I compared it to the new replacement plug.. worlds of wear on the old one. Kinda surprised I got it off, and it was a huge difference in comparison.

Still, if anything I left less than a pint in my block by lifting the rear. If flushing not enough to worry about. imo..

[kalevera]

a bit off topic but you can flush the block of coolant? i didnt know this. can the m30 do this?

The block has a drain plug, on the M30 it's on the right rear of the engine

[E38740iMD]

The block has a drain plug, on the M30 it's on the right rear of the engine

Oooooooh. So that's what that is. I thought it was the freeze plug I always read about