Overheated 300TDi

OK, bear with me for the scenario:

2 weeks ago the stud for the serpentine belt tensioner snapped and the belt came adrift. I got the truck home, replaced the stud and the belt as a matter of course. Belt was really tight to get on (right one chosen from measurements and VIN) but I assumed it was because it was brand new.

Had some squeaking after a few minutes of running but nothing too bad so I put up with it until I could get round to the penny trick which I assumed would be the problem.

Driving locally this week, and the temp gauge seemed to be all over the place, almost like there was a dodgy connection. But the main thing was the heater blower was not even warm. Engine seemed to run fine, so I carried on. On the way home, the needle moved up a bit then towards the red, but this time it seemed to stay up there. So I pulled over and stopped the engine. I gave it 10 minutes to cool down, checked the water (which was low), topped up the level and tried to start her. It would barely turn over.
My first thought was it was nearing seizure so I left it alone and called the rescue boys.

I had 2 thoughts as to the problem:

1. Big airlock causing the lack of reading on the temp gauge and also overheating.

2. Water pump foobarred causing no cooling, but would not explain apparent water loss (unless airlock as well)

I took the water pump off and although a little on the rusty side, the vanes are still connected to the shaft/pulley and there is no telltale of water from the weep hole underneath.

Also, in the process, one of the long studs holding the pump and alternator/steering pump bracket has sheared!

I checked manually for compression and it seemed good, so I attempted to turn the engine on the starter with the injection pump solenoid disconnected and it was fine, so I reconnected the solenoid and the engine started fine. I have checked for water in the oil and there seems to be no sign of it.

I would appreciate any feedback on what may be/have been the issue, and also any advice on removing the support bracket/pump carrier.

Sorry for the life story but it saves lots of questions after

Thanks in advance guys.

JB

There is quite an art to topping the water, have you searched this forum for the various methods? if you get it wrong the heater wont work, on mine i had to back flush the heater matrix and also fill it before going through the top up process, this fixed my overheating when towing, getting it right might be all you need to do to fix your overheating probel, if it doesnt ask away.......

should be easy to fill once thermostat housing plug is removed, check rads hot all over and if your getting air in its either leaking or head gasket is

Thanks for all the replies guys

Finally managed to get the alternator/power steering pump/water pump casting off after much effing and blinding. Luckily after a little judicious anger with the blow torch and a pair of mole grips I managed to get what was left of the sheared stud out.

Not sure whether to re-use the old pump or get a new one. So, do I replace the pump or re-use the old one? It looks reasonable and seems solidly attached to the shaft, but I would hate to fit it and have another issue.

Has anyone used 'lr-trade parts uk' on eBay? They have good feedback but I've no idea what the parts are like.

Any suggestions welcomed.

JB

id fit a new pump they are cheap compared to the hassle when they fail and youve done the hard work to get the old one out, i got mine from paddocks, but have not done many miles since. do yr best to stop the bolts seizing again.....:doh:

get new bolts. some will be rusted or have oil on them as they go into the engine block

Jonnyb1990 said:

get new bolts. some will be rusted or have oil on them as they go into the engine block

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Don't worry I will. After spending 3 1/2hrs getting what was left of one of the long bolts out of the bracket/housing I am most definitely replacing all the bolts and applying liberal amounts of copper grease to them all. It was not so much dissimilar metal corrosion as fusion of steel and alloy! B****rd of a job!

I'm just hoping that there was a BIG airlock and that's what gave the impression of losing water when it shifted and gave me the overheating issue. I can see no evidence of water in the oil at all, and she seems to run fine. So once I've refitted everything I'll take the advice given on here and another forum to fill and bleed the system.

Watch this space.....

Well, replaced the pump got everything back together. Bled the system as best I could.

The heater seems to work fine once the engine warms up, and the temp gauge sits around 1/3, but I am not sure the thermostat is opening. The large pipe from the pump to the radiator/expansion bottle gets hot, and the expansion bottle seems pretty warm. But the top hose from radiator to thermostat housing, and the radiator itself (apart from the end where the pipes connect) is cool. I have bled the radiator via the top cap, the thermostat housing via the brass plug but I cannot seem to get the top hose or radiator hot.

Any advice would be gratefully received

Squeeze the top and bottom rad hoses to circulate coolant and dislodge air,

coolant should come out Thermo plug (change to 1/2inch rad plug with bleed valve if you can)

Tip I learn'd from Pikey, top up the expansion tank completely, take truck for a run, dont turn off engine, bleed from 1/2 inch rad valve on thermo till coolant come out,

The excess coolant in the expansion tank will get out anyway once warm (the cap releases excess pressure at 14psi i think)

I have been squeezing the hoses to try and move the air, and also bled via radiator cap first then thermo housing plug and still no joy on getting the radiator warm. I always thought the thermostat would open once the water gets to 'normal' so as the engine starts to get hotter, the water would be circulating around the radiator even at a standstill?

yes, as long as the engine is running

SO I think I need to test out the thermostat, and if it works I guess I'll back flush the radiator and try again.

Johnny Disco said:

SO I think I need to test out the thermostat, and if it works I guess I'll back flush the radiator and try again.

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Sounds like you need a new thermostat - approx £4 - so why wouldn't you?

Easy job to do, just 2 x 8mm (from memory) bolts to remove and direct access to the 'stat.