perZ

Hi!


When taking the heads off my 350 TPI '89 the other week, me and my friend had problems finding the coolant drain plug on the engine block. From the description in the manual we only found one that matched on the middle of the lower part of the block's left side. When screwing it out there was no sign of fluid, all dry inside and acutally a little rusty. Could this be a frost plug? If so, where the heck is the drain plug?


We had drained the cooler previuosly but when taking off the cylinder heads it was obvious that coolant was still in the engine block since it came out of the bolt holes. This surpised us, should it be like this?


Thanks for helping out!


BR,
Per

UNCLE TOM

iTrader: (1)

sounds like you removed the proper plug . if you probe the hole you opened up you will find coolant . over time a skim layer of rust will build up inside the block . it's just the nature of the beast on a older engine . one more reason to flush cooling system every couple of years . do not forget re-install drain plug . good luck ...

sofakingdom

iTrader: (1)

There's another on the other side of the block as well, directly opposite... you MUST remove both (and knock the crusties out with a coat hanger wire or something) to completely drain the block.

Yes coolant should come up out of the head bolt holes. All 17 on each side go directly into the block water jackets. For this reason, when putting the heads back on, clean the bolts up real good with a wire brush followed by lacquer thinner; chase the threads in the block; and use Loctite/Permatex "High-Temp Automotive Thread Sealer with Teflon" on the threads and under the bolt heads.

TTOP350

iTrader: (8)

The one on the pass side is sometimes the knock sensor..

RBob

iTrader: (1)

What uncle tom said about the rust build up. Poke it with a screwdriver to get the coolant flowing. I am surprised that you were able to get the plug out at all.

They usually take quite a bit of effort to remove. I think GM puts them in with a impact wrench.

The right side of the block on your engine has the knock sensor in the drain location. Although the knock sensor is only torqued to 11 - 14 ft/lbs and usually come right out.

RBob.

P.S. typed this one in quick and still two replies ahead of me...

perZ

Hi again!


Thanks everyone for your quick answers! So it seems we took the drain plug out efter all. It's just so strange, no sealing around it and like I said earlier, not even a tiny sign of coolant -completely dry! The cooler had been drained just previous to removing the drain bolt, so I would have expected at least some damp.


There seemed to be more coolant in the right hand side of the block, judging from what came out of the head's bolt holes. There was still coolant in the holes of the left hand head bolt holes though. Is there any possisbility for the coolant jacket to clog?


BR,
Per

perZ

Hello!


No one ever heard of clogging in the coolant jacket, I take it?


Happy new year!


//Per

Camaro86IrocZ

iTrader: (1)

I opened mine up and think it was block filled with epoxy.

MoJoe

iTrader: (5)

Yes, 3 of the first 4 responses talk about crude buildup behind the plug, sealing off the plug, and needing to poke through the crude to get the coolant to drain.

BTW, the cooler is external from the block, so draining that might also drain the intake (which supplies the cooler), but not much else.
Disconnecting the water pump will drain the heads and top part of the block. The block drain plugs are for the coolant that sits below the water pump.

perZ

Alright, I follow you now Will have a go and see if rust build-up can be the cause. What I meant in my last post was if the whole jacket could clog, so that coolant couldn't reach for example the left side of the block (which I guess would be disasterous). If that would have been the case though, I probably wouldn't have been able to suck coolant out of the left head's bolt holes, right...


Thanks again for all your help guys!


//Per

bigal55

iTrader: (1)

If you look at a bare engine block, the area below the camshaft is almost completely open. The only small water jackets are in the block sides. The main water jacketing is up in the head area and is where most of your heat transfer takes place. The drain plugs in the bottom sides of the block only drain the smaller water jackets below the water pump level, as stated above by MoJoe. Yes those smaller water jackets could become completely blocked but in that area of the block probably not cause too much of a problem. The main cooling around the heads and cylinders is much more critical and is provided by larger water jackets which would not clog up so easily. This all depends on age of the engine and maintenance of the cooling system as stated by UncleTom. Probably a good idea to get your system flushed and new anti-freeze installed.

perZ

Thanks a lot bigal55!


One more thing: if I manage to poke some rust build-up off inside around the plug, isn't there a risk for that to get trapped in the system and cause trouble for the coolant flow either in the jacket or radiator?


The system is dry now since I sucked the remaining coolant out through the holes.

bigal55

iTrader: (1)

If you want, you could loosen up the scale and rust with a wire as stated by SofaKingdom. Afterwards, you could flush all the loose stuff out the block drains but in reality you are not going to be able to make that much of a difference with just plain water. You should have the system flushed later.

perZ

Gotcha -thanks!