Never should have modified
Submitted: Thursday, May 03, 2007 at 14:02
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45051
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Member - Carl L (VIC)
Help required! Have had a 350 Chevy V8 + 300 Turbo Auto + gas/petrol fuel system fitted to a '84 diesel (was) HJ47 Troopy. Surprise-surprise the rig runs hot!! Radiator has been upgraded and thermo-fan installed. At 100KPH the engine is about 3000RPM - Question: 1) can the over-reving be reduced by modifications to diffs and/or trandfer box?? 2) what is the litre water capacity of the V8? I measure about 4 litres ~ maybe it's blocked?? Suggestions other than a box of matches will be appreciated
Reply By: banjodog - Thursday, May 03, 2007 at 15:34
Thursday, May 03, 2007 at 15:34
Cooling fans are only useful at 20km/hr or below – above that speed normal air flow by the vehicle’s road speed is only needed. Have you installed a lower opening temperature thermostat?
I installed a 307ci in an FJ40 back in the early ‘80s and the radiator I had custom built was five (5) cores wide and held a lot more than four (4) litres of coolant your stating and I didn’t have any cooling issues.
As for your diffs – you can fit higher ratio ones that will do the trick or fit a 4 speed auto that has overdrive like the TH700R4 out of a Commodore VP.
AnswerID:
237664
Follow Up By: Member - Carl L (VIC) - Thursday, May 03, 2007 at 18:29
Thursday, May 03, 2007 at 18:29
Again many thanks ~ I've been misleading - the radiator capacity is a little over 3 litres and another 4 for the motor ~ seems too little? someone has suggested installing a header tank to increase the volume - the thermo fans appears to work OK ~ with motor stopped - from boiling to thermo cut-out is about 4 minutes with cut-in maybe another 4-5 minutes accounting for convection?
FollowupID:
498774
Reply By: Gerhardp1 - Thursday, May 03, 2007 at 16:11
Thursday, May 03, 2007 at 16:11
Friend has 350 Chev in a 60 series.
Had overheating problems until -
1) Fitted a Marks 4WD adapters adapter to run the original toyota viscous fan on the 350.
2) Modified a 60 diesel shroud to enclose the fan and hence provide decent air flow.
3) New radiator fitted to replace the original 60 series one, which had 2/3 of its channels blocked.
I also second the suggestion to fit the TH700 box. With the 4.1 diffs you should then have about 2300rpm @ 100k. Low Low will give you engine braking down steep stuff like you wouldn't believe, as the 700 has very low 1st and reverse ratios.
AnswerID:
237672
Follow Up By: Member - Carl L (VIC) - Thursday, May 03, 2007 at 18:31
Thursday, May 03, 2007 at 18:31
Again thanks ~ With all the good advice I'm sure the problem will be solved
FollowupID:
498776
Reply By: Wayne-o - Thursday, May 03, 2007 at 17:14
Thursday, May 03, 2007 at 17:14
cARL
I have a 350 chev in my SS ute.
4 litres wont cool the cigarette litre on that donk.
Mine has 14 litres capacity in the radiator.....10 more than yours...this is your problem!!!!
Go to the wreckers...forget toyota radiators, and get one out of an SS of something that is fitted with a GEN111 V8.
Then fit a thermo fan, 10" or something....some of the best coolant you can get ya hands on, and never worry about it again
GOOD LUCK
AnswerID:
237689
Follow Up By: Member - Carl L (VIC) - Thursday, May 03, 2007 at 18:38
Thursday, May 03, 2007 at 18:38
Hi Wayne ~ my misleading the total current coolant capacity is 7 litres. The current radiator is a custom job (probably an adapted FJ45) to fit the narrow frame space - moved forward to accommodate the thermo fan. Any comments on a 'header tank'?
Thanks for the support
FollowupID:
498778
Follow Up By: samsgoneagain - Thursday, May 03, 2007 at 21:53
Thursday, May 03, 2007 at 21:53
wayne you doodle brain. the total contents of the cooling sysytem is also the amount out of the head and the heating system too . i think a landcruiser is about 16 litres. ok ok
FollowupID:
498855
Follow Up By: Wayne-o - Thursday, May 03, 2007 at 23:32
Thursday, May 03, 2007 at 23:32
OOPS....
ha ha.....thats kinda what i meant....the raiator on it is massaive, bigger than my pootrol, and 14l comes from specs in manual......
FollowupID:
498886
Reply By: Member - Stephen M (NSW) - Thursday, May 03, 2007 at 17:23
Thursday, May 03, 2007 at 17:23
Hi there Carl, Firstly I would remove the electric fans to the front of the rad and reverse so they push air through the rad and have them for back up. As said above I would go back to a viscous fan set up. Possibly one off a VC/VH/VK commodore motor will possibly match the threads up to the chev water pump and make sure the one you get it from ran air con as they have a much bigger pitch and bigger blades and for memory 7 blades. When these suckers cut in sounds like a jet taking off they pull huge amounts of air and will outdo electric fans full stop. As far as fans not working above 20klm that is crap. If the engine is hot enough and the outside air is hot they will cut in at whatever speed to cool the radiator water temp down. When I replaced the viscous coupling on my hilux I could hear it (even over the old 2.8D) cut in and out on hot days even at 100klms. They work by the air temp passing through the radiator and onto the small spring at the front of the coupling. If it detects the temp higher then the preload set on the spring from the factory it will cut in. Ive only had my prado about a month and I could hear my fan cut in at 85klm pulling up the hills coming back from the south coast. As I was putting the boot into it and had camper in tow. BUT if your saying you are only getting 4 litres out of the cooling system you have a blockage. One way to tell is when it gets hot is pop bonnet and run your hand over the face of the radiator (turn off motor) and feel if any of the radiator feels alot hotter in some
places then others. It should always feel cooler at the top as it will have passed through the radiator from bottom to top and cooled in the process. This is how I found my old VL commodore rad to be blocked up. But 4 litres no way should be more like 10 if your including motor and radiator together. Regards Steve M
AnswerID:
237694
Follow Up By: Member - Stephen M (NSW) - Thursday, May 03, 2007 at 17:35
Thursday, May 03, 2007 at 17:35
Sorry that should be water coming out the top and get sucked in through the bottom hose radiator should be cooler at the bottom not the top. Totally the opposite way round was thinking of my water jackets that I use at work. Regards Steve M
FollowupID:
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Follow Up By: Member - Carl L (VIC) - Thursday, May 03, 2007 at 18:46
Thursday, May 03, 2007 at 18:46
Hi Steve
I thank you and all the others for the support! I guess your've seen the comment re 7 litres vs 4 litres! Still low?? The radiator is OK as I have had it professionally opened and checked. I'll absorbe all the comments, reach for the matches and let everyone know the results!!
FollowupID:
498782
Follow Up By: Member - Stephen M (NSW) - Thursday, May 03, 2007 at 19:21
Thursday, May 03, 2007 at 19:21
No doubt you have, but have you removed the thermostat just to make sure its not that. I have replaced old thermstats with new ones over the years and have had a dodgy one that was opening far to late and running hot. Obviously there is no obstructions in front of grille
driving lights etc blocking air flow. Does it have air con ?? if you have changed over radiator maybe fins arnt matching up there fore air not going directly through the air con condensor then radiator. I think what has been said previous about getting a radiator from a gen3 engine and fitting if possible. I know even ignition timing will make them run hot if its out but not normally to that extreme. As said above do you have a shroud fitted so its pulling air through the rad and not sucking around it eg hot air already around engine bay. Presume water pump is correct one and in good nick, It might pay to pull out and make sure all the fins are ok. Was a new one installed when you had the motor done. Maybe the impellor is slipping on the shaft and not turning properly although they are normally one piece. I had a chev in my
old car so just trying to think why it would be running so hot. I never had any issues except on 35/40d days but still wouldnt overheat just run warmer than normal. Will ask my other mate hes a chev nut will show him this web page and he can have aread maybe might come up with some thing. He also races and knows a reasonable amount about chevys. It sounds like its not holding enough water in the system my VX commodore use to hold 11 litres V6 ecotec motor. Problem even with a say five core radiator its still only narrow so all the heat is in a small area instead of spread across. My wifes new car the radiator is a wide as between the headlights and only singe core. I think over the years they have realized that the wider the better not neccisarily the depth as hot air is getting pushed through say 5 cores but maybe only 50cm wide where as now I have noticed alot of the new cars are say 1M wide but only single or double core but obviously the water spends more time in the radiator cooiling down. Just my opinion thats all trying like the others to give you some thing else to
check out. Regards Steve M
FollowupID:
498789
Reply By: mrbasilbrush - Thursday, May 03, 2007 at 19:32
Thursday, May 03, 2007 at 19:32
Hi, Carl I had a 327 chev in an FJ40 shorty back in the 80`s and never had heating issues.
Although It had a 2" twin system exhaust system which expells hot air exhausts quickly.
If you have a small restrictive exhaust sytsem it willl contribute to heating.
If it is a genuine toyota muffler get rid of it quick smart.
Get a 2" exhaust fitted and new muffler.
Check your timing, that can make a huge heating issue as I have experienced, I had a mild cam in
mine and advanced the timing by 8 to 10 degrees for best performance.
If your radiator is too old get it flushed or get a new one.
If you have gunk in your radiator core it will contribute to overheating .
AnswerID:
237731
Reply By: Boldjack - Thursday, May 03, 2007 at 22:52
Thursday, May 03, 2007 at 22:52
Hi Carl
If you consider the fact that even your everyday 6cly falcon or commodore requires about 12 to 14 litres of coolant , you can't expect your set up to cope with towing and off road conditions, even with extra fans.
I don't know how much water a small block chev holds but that doesn't seem enough.Maybe your not allowing for what stays in the bottom of
the block.The bigger radiator option mentioned earlier sounds like a good one.
If 7 litres is all you have I think it would have to circulate too fast through the system ,therefore not spending enough time in the radiator to cool down.
Good luck.
Boldjack
AnswerID:
237788
Reply By: Ron George - Friday, May 04, 2007 at 08:06
Friday, May 04, 2007 at 08:06
Hi Carl, I think your problem has pretty
well been solved, heaps more coolant, & greater air flow, if you still experience problems after that might be worth checking the actual efficiency of the water pump, impeller clearance is fairly critical in pushing the required volume of coolant around the system. to
check that a pressure gauge needs to be fitted, usually where the rad cap goes, it should make around 8 to 10 PSI at say 1500 RPM any thing less & the pump might be a bit dodgy. Good luck Cheers Ron.
AnswerID:
237824
Reply By: traveller2 - Friday, May 04, 2007 at 08:23
Friday, May 04, 2007 at 08:23
Not sure whether this applies to petrol Chev motors but in the diesels it is possible to fit the wrong waterpump.
The early motors with V belts for the ancillaries run in one direction and the later donks running a serpentine belt the waterpump is actually turning in the opposite direction due to the belt route around the pulleys.
It is very easily done especially if a new water pump is fitted as part of a rebuild as there is no difference between the pumps except for the impeller casting/flutes on the inside.
Having the waterpump running in the wrong direction does absolutely nothing for the cooling!
AnswerID:
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