Timing Belt Change -- Page 5
Replacing Cam Seals & Alternator
Replacing PCV Valve
Waterpump and Thermostat
Replace Timing Belt and ReAssembly
Timing Belt Change -- Page 2
Timing Belt Change -- Page 3
Timing Belt Change -- Page 4
Changing the Spark Plugs
Timing Belt Change -- Page 1
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Mitsubishi 3.0 SOHC Engine

Replacing the Waterpump and Thermostat

This part assumes you have already disassembled the front of the engine and removed the timing belt; Pages 1-5 in this guide.

First, drain the cooling system. I found this somewhat difficult in the minivan, as I could not locate a drain with a turn cock. I ended up loosening the return hose from the engine (near L front wheel) and draining it out gradually. Not elegant, but it worked.

The radiator is way to the L front of the engine compartment on this car (oval). The arrow shows the destination of the return coolant line and the thermostat housing.


Now, back to the front of the engine. Remove the timing belt tensioner spring. Don't lose it! This is the view from above.


The waterpump is held on by 5 main mounting bolts (circled), with some smaller bolts connecting the 2 halves together. The gasket which mounts the waterpump fits over the 2 engine mating areas at either end of the pump. In the back, the pump intake fits on the inlet tube with an o-ring for watertight integrity.



In this last picture, you also see a machine bolt sitting at the top (bottom in the picture) of the waterpump. This bolts on to the very troublesome rear timing cover/alternator bracket which must be removed to access the rear cam seal. If you have already replaced the seal, then this is the time to do the waterpump -- before re-assembly.

Note in the diagram below the position of the gasket and the location of the o-ring (courtesy of the Haynes manual).


Here is another view of the bolt attaching the rear timing cover/alternator bracket to the top of the waterpump. This was the single most annoying piece to remove from this engine. If you are just doing the waterpump and don't want to remove this beast, you should be able to simply loosen the bolt and slide the waterpump out. Clearance of the bolt head may be an issue.

The arrows point to the bracket arm that attaches to the waterpump. The bolt is just out of sight above the pump pulley.


Remove all of the mounting bolts and slide the waterpump off the crossover coolant tube in the back, and unbolt it from the rear timing cover/alternator bracket (if still in place). Clean the mating surfaces with the engine and the crossover tube, removing old gasket material.

On the new waterpump, apply a layer of black RTV to the pump mating surfaces, and lay the gasket in place. Add additional RTV to the other gasket surface that will abut the engine. Don't forget the new o-ring in the back. Then, pop the back on to the crossover tube, and line up the rest. Torque the bolts to spec.

In this picture, you can see the top mounting bolt for the rear timing cover/alt bracket sitting all by itself on top of the pump.


That's it for the waterpump. With the cooling system empty, you should replace the thermostat also. I used the 195F degree thermostat, which is stock.

First, remove the return feed tube from the curved thermostat housing. Expect a little leakage of fluid. Next, unbolt it from the underlying structure, and remove any gasket material. Take out the old housing.


Now, put the new gasket in as shown below, with a little black RTV to assist. The Haynes manual says "align the thermostat bridge with the casting wall". This was greek to me. I put it in the same way the old one came out.


A little RTV on the new gasket, and re-bolt the thermostat housing back into place. Re-attach the feed hose from the radiator, as well as a few other minor sensor ? lines that you have to temporarily disconnect or move. Now is a good time to fill the cooling system.


Here is the final waterpump assembly, all ready to go.


If you already had to disassemble the rear timing cover (rear of engine compartment), this is a good time to remove and clean both rear timing covers. And maybe tackle the cam seals. I found it hard to assess the condition of the cam seals without removing the cam sprockets.

Anyway, the cam seal replacement is a bit of a pain. However, you are most of the way there already. And you get to replace the alternator as a bonus too, as well as expose the number one spark plug for replacement and checking TDC position.

Replace the Cam Seals and Alternator

Replacing the Timing Belt and Re-Assembly

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