Overheating... at a loss...

[mjktng]

This will be kind of lengthly I will try to keep it as short as pos with out leaving out details. I have a 95' camry 4cyl dohc 2.2. It all started with an over heating issue. I started with the standard test removed the rad cap and saw bubbles. Ok I have a blown gasket. Tore down replaced the gasket cleaned the head, put it all back together. Still over heating, removed thermo (no help there) I was trying to be frugel, it backed fired on me. So I took it all apart again had the head tested and resurfaced took 6000th off. Put all back together again with another gasket and head bolts. This time with no thermo in (still no help), better, but not right. Took rad cap off no bubbles, but also noticed no flow. Disco top rad hose filled the engine with antifreeze then the rad and then topped off, started car and with upper rad hose off no flow from upper rad hose. Thought blown water pump, replaced with new and all belts. After driving for about 15 min stop and go started to get hot. Drove on the highway got hotter, back to city roads it cooled down but still above the halfway mark. Once again this is w/o the thermo in and coolent switch for fan unplugged forcing the fans to stay on. Next thought was clogged system, emptied the rad, disco the upper and lower rad hose put a garden hose in the upper rad hose port and ran water it had a nice flow. I then did the same thru the engine still had nice flow. I then reconn everything but the upper rad hose refilled everything. I then put a garden hose in the upper rad hose port on a low pressure just to keep water in the system started the car to see what flow was there. It had very little flow from the upper rad hose. I am stumped... No clue where to go now. Any and all suggestions will be helpfull. Thanks.

[JohnGD]

So the garden hose showed good flow in the engine block and radiator, but low flow when the water pump tried it?

Maybe the thermostat needs to be there to block off an internal bypass so the coolant can better flow out toward the radiator?? Have you tried putting in a new Toyota thermostat? No aftermarket stats here.

See with the new stat operating what kind of flow you get at the radiator/heater core.

Then check for ignition timing. If it's timing then it's probably too retarded, because if it was too advanced the pistons will get burned and you would have noticed it doing the head gasket.

[Stillrunning]

One note is that the engine can run hotter without thermostat because the water flows too quickly through the rad to remove heat from coolant.

[mjktng]

Originally Posted by Stillrunning

One note is that the engine can run hotter without thermostat because the water flows too quickly through the rad to remove heat from coolant.

I thought about that but im not getting any flow, almost like the water pump isnt working.
Just as an added note the old water pump wasnt bad, I just replaced it cause it was out and I had it.

[BamZipPow]

Time to scope the cooling passages and see if there's something blocking the flow.

[toddub]

I just rebuilt my 1997 5SFE Engine with parts from a 1996. The 1996 engine had overheated. While disassembling the engine I noticed the aluminum water pump lines were filled with a white chalky substance. One of the two lines was completely plugged up.
Perhaps you have a warped or cracked cylinder head or some kind of air leak in the system....

[sam333]

When you pulled your head gasket the first time , did you see where it was blown at( was it obvious)?

Did you check the block deck for flatness?

I know this does not address the flow problem you describe. Its just unusual( suspicious) to have two major failures( head gasket, new water pump( water flow) at the same time.

Do you know what the proper flow should look like with hose off and the pump running? Do you have a baseline for comparision? If you do, and its not flowing like you know it should, then I would remove the new water pump (check it, make sure its the right type )and replace it with your old one and see what happens.

[camrtm3]

The more important question to all of this is how long has it been overheating. The head is aluminum and the block is iron. By having the two metals over heat time after time again is that they expand and contract at different rates. If this thing has over heated for a long period of time the block and head are warped and you need a new engine.

Sorry for the news on that. Happens a lot to the MR2 5S-FEs. At least the ones in MD.

[sam333]

The reason I asked about the deck is ,if you blow a head gasket its recomended to at least check the block deck for flatness( so you dont blow another head gasket).

Like what was mentioned above, if it overheats badly ,the head and the block can be warped. Also careless cleaning( using abarasive pads on air tools can cause dishing, dips in the block( even iron block) so the new gasket wont seal.

All of those are usually repairable by having them resurfaced though.

I am mentioning this because I have seen so many head gasket jobs go bad from not checking the head and the block.

Also can your head gasket be installed bacward( some toyota head gaskets will fit on that way ,but cooling passages will be blocked).

Is there alot of corrosion ( rust ), scale, sediment in your cooling system?

Make sure hoses are good and not collapsing.

Dont run without a thermostat

Check your engine for back preasure( dented exhaust pipes or blocked exhaust).It can cause overheating .

I was tearing down an engine a custumer had exchanged for a rebuild, ( he had a chronic overheating problem that no one could figure out) when I pulled the freeze plugs and looked into the cooling jacket .I could see all the freeze plugs from the previous rebuilds. They had bunched up and had been blocking the flow of coolent. Instead of pulling the plugs they just drove them into the block, I fished them out and counted two sets of plugs( it had been rebuilt twice before he got it).