Hitachi zx 25 overheating...

A

Alan caddy

Active member
I have also seen impeller doing that, at least if no flow you know straight away, there is a tap beside thermostat housing that switches of flow to heater make sure that's open to increase water circulation to see if it makes any difference
 
GazCro

GazCro

Well-known member
Is it using water? If your going to the hassle of taking water pump off to check impellor which may seem ok when cold anyway I'd price a new water pump first. If not silly expensive might be worth changing anyway while you've gone to the hassle of removing it.
 
Hg2702

Hg2702

Well-known member
Edit, I see your only at Bovey Tracey..... Buy the Combustion test kit. PM me your phone number and I will pop up and look next Friday night if you want..... No charge to look see but a donation to my beer fund is appreciated if the problem is solved.
Another local 🙋🏼‍♂️
 
JD450A

JD450A

Feral as Fk
Is it using water? If your going to the hassle of taking water pump off to check impellor which may seem ok when cold anyway I'd price a new water pump first. If not silly expensive might be worth changing anyway while you've gone to the hassle of removing it.

There is some witchcraft to check it before removal Gaz, 🥰 will only get certainty by removing it throwing in a bucket of boiling water and checking it though.
 
GazCro

GazCro

Well-known member
There is some witchcraft to check it before removal Gaz, 🥰 will only get certainty by removing it throwing in a bucket of boiling water and checking it though.
I wouldn't go for taking it off before being more sure that it's the issue.
 
JD450A

JD450A

Feral as Fk
I wouldn't go for taking it off before being more sure that it's the issue.
Thats the trouble with all "mechanics" these days is the penchant to fit new bits until it works.

Issue is as soon as you start ripping something to bits you can't diagnose it....Temperature issues have 4 general causes - Airflow, Water Flow, Constrictions and Outside Heat.

My guess personally is it's a outside heat issue, either via the hydraulic oil cooler or Head gasket. Water pump seems unlikely as 10 minutes should not heat the coolant up that quickly, the Merc 1317 that had that issue would do a 30 minute trip before it started boiling.
 
GazCro

GazCro

Well-known member
Thats the trouble with all "mechanics" these days is the penchant to fit new bits until it works.

Issue is as soon as you start ripping something to bits you can't diagnose it....Temperature issues have 4 general causes - Airflow, Water Flow, Constrictions and Outside Heat.

My guess personally is it's a outside heat issue, either via the hydraulic oil cooler or Head gasket. Water pump seems unlikely as 10 minutes should not heat the coolant up that quickly, the Merc 1317 that had that issue would do a 30 minute trip before it started boiling.
There are very few mechanics about now tbh that's a fact.
 
craig

craig

Well-known member
Edit, I see your only at Bovey Tracey..... Buy the Combustion test kit. PM me your phone number and I will pop up and look next Friday night if you want..... No charge to look see but a donation to my beer fund is appreciated if the problem is solved.
This is a very good offer, well done Rory.
 
Left hooker

Left hooker

Well-known member
A guy I know who repairs machines / tractors did a Hitachi 22u the other day for over heating he flushed it out several times that seems to have cured it
 
V8Druid

V8Druid

do it as well as you can,but learn to do it better
A guy I know who repairs machines / tractors did a Hitachi 22u the other day for over heating he flushed it out several times that seems to have cured it
yeh could well be sludged up if it's stood about much and the recent weather'll been no help in the temperature stakes ... only neds one gallery to be constricted to upset the whole flow and cause a hot spot, which'll spread fast
 
Left hooker

Left hooker

Well-known member
yeh could well be sludged up if it's stood about much and the recent weather'll been no help in the temperature stakes ... only neds one gallery to be constricted to upset the whole flow and cause a hot spot, which'll spread fast
The guy I know said he used rad flush acid and power washer in top of rad several times as the cores are so small it don't take much to clog
 
Mick-the-fitter

Mick-the-fitter

Active member
Looking at it, it seems to be Yanmar 3tna engine, when running does it black smoke when you use any lever?
 
Mick-the-fitter

Mick-the-fitter

Active member
Had plenty of tan’s running with head gasket gone between the cylinders, run fine, til under load, the one hard working cylinder, runs black smoke and gets very hot trying to drive everything, and push the lazy two up and down, (compression test)
 
C

Canal Navvy

Active member
I see that Rory thought head gasket failure was likely for that model. ;)

That one working cylinder would be burning excess fuel on the piston crown so would get very hot quickly (as discovered by over enthusiastic re-mappers :p)

Sounds a good shout, looking foward to hearing how it goes.
 
W

Will zaxis 25

New member
Edit, I see your only at Bovey Tracey..... Buy the Combustion test kit. PM me your phone number and I will pop up and look next Friday night if you want..... No charge to look see but a donation to my beer fund is appreciated if the problem is solved.
Sorry I've only just seen this.... If the offer is still there I would definitely appreciate that. I have the combustion test kit, there didn't seem to be any air coming out of the rad (which I guess is good!) however feeling the oil cooler rad when the engine is hot, I can touch it easily and the inlet/outlet pipes seem the same temp(just very warm, not "boiling" hot.
 
W

Will zaxis 25

New member
I have also seen impeller doing that, at least if no flow you know straight away, there is a tap beside thermostat housing that switches of flow to heater make sure that's open to increase water circulation to see if it makes any difference
The heater is blowing hot air👍
 
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