Leaderboard

The 25D has head gasket issues for one reason only - the bore diameter caused a reduction in the thickness of the cylinder liner support walls where the HG fire ring seats on the block. Due to the thickness of the composition graphite gaskets they started with in 1996 (because of piston height above the deck at TDC) there is insufficient rigidity provided by the cylinder head to prevent the cylinders from moving around due to thermal expansion and contraction and combustion chamber pressure.This movement abrades the fire ring against the block and head leading to pitting, which ultimately leads to failure. Number of heat cycles is the primary indicator of lifespan coupled with any overheating events that add further thermal stress loading. It is easy to see this because Subaru solved the problem - you only need to look at what they did to effect a solution. They changed the piston to allow a thinner head gasket, and they beefed up the block around the liners to make them more rigid. For turbocharged applications they incorporated liner gussets to help stop them from moving under high cylinder pressure and temperature. Also the open deck 1.8 and 2.2 engines do not have this problem despite having the same thickness HG as the earl 25D. Why? Because the cylinder liner support walls are WAY thicker due to smaller bore size. The engineers that designed the EJ never envisioned a 2.5 liter displacement when they modeled in on early computer systems in the mid 1980's. When new engineers were asked to increase the displacement they inadvertently caused a HG issue by the bore size change without considering what that would do to the rigidity of the cylinder. It was an engineering design mistake. Nothing more. Nothing you do or do not do as regards the thermostat location will have ANY effect on the HG "problem" associated with this engine. Want to solve it permanently? Resurface the block and the heads, Install 251 pistons, and use the 642 turbo head gasket. They will never blow again. GD

Here is the situation. 99 legacy filled with coolant, ran half hour with funnel full of coolant until bubbles came out, fans cycled many times, released any bubbles from right side upper plug on radiator. Car drives without overheating for long periods without leaking. Shut the car down, come back out and there is an 8 oz puddle under the car under left side front of engine timing cover. Replaced the radiator. Coolant is 50/50 mix. Radiator is new and no leaks there. New cap. Eventually lose enough coolant that we are back at refill and bleed. Is the water pump my problem? Not looking forward to that job as the timing belt cover bolts are very rusted and won't come out easily.

A vacuum leak sucking air & needs to be plugged? My Sube had that recently, kind of a whistling whine.

sounds like water pump or t-stat housing. closely inspect the area i suspect you should be able to see a wet spot where its coming from. it could even be a loose hose clamp on the lower hose.

Yes that is the correct pump for the EA81. Congratulations on finding one. GD

So you installed a new pump into the existing pump assembly? The pump assembly has a metal cap over a pressure chamber - this cap is a known failure point. The ears that hold it to the plastic housing will tear off and the pump pressure blows the o-ring out. There is later model that has a filter in that position on the assembly and you can buy the filter which comes with a new (larger, but it doesn't matter) cap with stronger ears. You use that cap and a new o-ring to fix this failure. Or you buy a new assembly. GD

It looks a bit odd, but I never had an EA81. It doesn't look like earlier or later ones though. The 2 steps look funny to me. The earlier pumps and the ea82 pumps have one round part past the flange, and a short shaft sticking out.

Bypass the heater core. Restricted heater cores can reduce coolant flow to the back side of the t-stat not allowing it to open.