04 OB Heating at high rpm

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leeton1203
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04 OB Heating at high rpm

Post by leeton1203 » Wed Dec 28, 2016 7:03 pm

iv got a 2.5 OB new engine thats got 150 000 on it. the old engine i took out was ran dry on oil and there was dirty water in in when i removed it.

iv put the new engine in and it seems to run fine, no bubbles or anything like that to indicate a head gasket.

flushed and reversed flushed the radiator, new fluid, thermostat and cap.

ill drive the car around town, no problem, AC on and everything. start going down the freeway and the temp will rise to just below 3/4 and maintain, may rise or lower depending on the rev range will get slightly hotter at higher rpm. ill then come back into town and drive around and the temp will drop back down to just under natural. it will sit and idle fine, every thing seems ok except that sustained high rpm of freeway driving....driving at 90 was better...but still eventually raised to the 3/4 mark. dosent mater hot day or cooler evening, seems to stay the same.

your thoughts on this would be greatly appreciated as I'm fast running out of ideas.

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El_Freddo
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Post by El_Freddo » Wed Dec 28, 2016 9:00 pm

Any coolant loss?

Still got the plastic "bash plate" fitted as per factory?

If you don't have anything there is suggest refitting the plastic piece that used to be there. This will have a dramatic effect on the draw through effect at speed.

Other things to look at would be the water pump - genuine or aftermarket? Aftermarket gets a pressed steel impeller, genuine gets a cast unit that's much much better at flow and reduced cavitation at high revs compared to the pressed steel impeller unit.

Other thing to check - heater work good? Adding a "H" block into the heater lines can sometimes reduce engine heat by allowing some coolant to bypass the heater core.

I'd start with the simple stuff and go from there.

Cheers

Bennie
"The lounge room is not a workshop..."
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leeton1203
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Post by leeton1203 » Mon Jan 02, 2017 6:37 pm

there dosent seem to be any coolant loss.

i still have the bash plate fitted, but not sure about the water pump, can't really see and i don't know the history of the engine other then i was told that it runs well....which it does just gets warm at speed.

The heater does work well...i was going to put the H block in as that was a really good idea as i thought that the heater core would be the issue...i had the wrong size connectors so i just bypass the core all together, as that had worked in my old liberty, but still did the exact same thing, 2 k down the free way and she got warm and levelled out at 3/4, jumped of the free way cooled back down to just below natural.

i just gave the car a run with the guts of a thermostat removed to allow full unrestricted flow, but again warmed up at exactly the same spot and response.

it has been suggested that it is the head gasket by a subaru mechanic friend of mine...but the standed signs of a head gasket aren't there?

I'm thinking i might change the water pump and do a timing kit while I'm at it as i don't know if the car has had one as its got 150 000. where is the best place to get original parts?

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El_Freddo
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Post by El_Freddo » Mon Jan 02, 2017 6:54 pm

Original parts sources are varied. There are sites in the US that can be good. Contacting FROG here on the forum is a good start too.

When was the radiator replaced last?

And an EJ popping a head gasket can be subtle. It happened to me, it didn't use coolant or blow out the overflow bottle but it would run very hot in the same situations.

If they've not been done, do them. It'll give you peace of mind and if they have popped you'll get them before any serious head damage is done.

Cheers

Bennie
"The lounge room is not a workshop..."
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