Really stumped on a turbo'ed om602 overheating issue

[pgh13]

I've seen some YouTube where they fill the cooling system on a Porsche by pulling a vacuum on the system; hoses sucked flat and then let the coolant be sucked in, eliminating the chance of airlocks.

 

[clarkmichigan55b]

Just looking through reply 26 to my previous question and you said " NO OVERHEATING BEFORE CONVERSION". I know you said other people have done conversions on these motorhomes and had no problems.
Could a combination of adding a turbo + over drive gearbox + larger wheels + the size and weight of the vehicle is causing the problem.

As far as i know the T1 Bremen series was not fitted with a turbo charger from the factory but i stand to be corrected.

I have had my van from new and have had no overheating problems. Yesterday 26th on the hottest day of the year, i had a trip to Weymouth Dorset over 120 miles the temperature only went up to 3/4 on the gauge when climbing hills but returned quickly to normal on the flat the VC fan did NOT cut in.

The engine is still on its original heater hoses after 30 years with original radiator but the water pump and thermostat have been changed with Mercedes genuine parts, but i did have to change the head gasket some years ago. Antifreeze has been change every 3 years with a 50% mix. The heater hoses do have the Mercedes logo and may have a part number stamp number on them.

You have to remember that these are commercial vehicles and were set up from the factory to be just that not pocket rockets. I know that the world is a different place with engine technology and all vans now have turbo charging in some form or other.
I am a great believer in keeping it standard.

Adrian.

 

[Roxie]

Feel round the radiator after a run if you find cold areas its blocked. They allways suffered from this and up hill is when you would first notice it.

 

[Rockron]

Just looking through reply 26 to my previous question and you said " NO OVERHEATING BEFORE CONVERSION". I know you said other people have done conversions on these motorhomes and had no problems.
Could a combination of adding a turbo + over drive gearbox + larger wheels + the size and weight of the vehicle is causing the problem.

As far as i know the T1 Bremen series was not fitted with a turbo charger from the factory but i stand to be corrected.

I have had my van from new and have had no overheating problems. Yesterday 26th on the hottest day of the year, i had a trip to Weymouth Dorset over 120 miles the temperature only went up to 3/4 on the gauge when climbing hills but returned quickly to normal on the flat the VC fan did NOT cut in.

The engine is still on its original heater hoses after 30 years with original radiator but the water pump and thermostat have been changed with Mercedes genuine parts, but i did have to change the head gasket some years ago. Antifreeze has been change every 3 years with a 50% mix. The heater hoses do have the Mercedes logo and may have a part number stamp number on them.

You have to remember that these are commercial vehicles and were set up from the factory to be just that not pocket rockets. I know that the world is a different place with engine technology and all vans now have turbo charging in some form or other.
I am a great believer in keeping it standard.

Adrian.

My Post #44 makes much the same points, I've used the om364 4L as an example.
Viz. to improve the power output of the naturally aspirated engine by incorporating a low pressure turbo, MB also had to make a number of significant additional tech./engineering modifications to maintain reliability, and presumably prevent
overheating.

Significantly, this only upped the power output by 18bhp, perhaps surprisingly
MB didn't add an intercooler, although I'm not certain if the radiator was
upspecced. They added an intercooler when they upped the power an
additional 18bhp.

I know some motorhomers with the 410D 602 did little more than add a
turbo, I suspect it's these very basic conversions that over the years I've heard
(a few I know for certain)were prone to overheat and expire. Brightonside has an intercooler and this may well be sufficient to prevent overheating, assuming it's
fitted in an effective position and no blockages.
The thing is what did MB do to that 410D engine and ancillaries (besides fit a turbo) to make it a 412D?

 

[Brightonrider]

Thank you for the advice but, as said before, the van will overheat with little to no boost. I am not labouring the engine and the radiator is barely warm at the lower hose.

What was changed at the same time as the turbo conversion:

- new thermostat
- new radiator
- new rebuilt diesel pump with 6mm elements
- new viscous clutch fan

My initial thoughts made me think maybe the pump timing could be off and cause the overheating but the van could not run smoother and it starts on half a turn of the key.

The garage has reversed flushed again the engine block and the drilled thermostat has been put in and I am going to do some extended test driving. I will report back with my findings.

 

[Kev555]

Thinking what PGH13 said was very close to the mark, Stat is throttling the flow which needs to be faster now the turbo has added to the heat dissipation from the engine. Holes in stat achieves that, I suppose if you reduce or add the amount of holes to the stat you will find a happy medium on engine temp or a lower temp or larger aperture opening stat. I talked to my friend that had the campers, alas they were all standard spec he had and anything he worked on belonging to others so no issues of overheating from him.

 

[clarkmichigan55b]

Just out of interest what have you set the injection pump timing at?.
And have you spoken to Diesel Pump UK for some pointers.

 

[Brightonrider]

Follow up to this - so, have now fitted a long reach radiator cap and a new bottom radiator hose. Also, done a dishwasher cleaner flush which I ran for 100 miles. Currently the motor is running with a gutted thermostat and I cannot get the motor to overheat on any incline I can find. I have yet to get it to pass the halfway mark on the water temp gauge. The temperature gauge movement is nice and slow.

Next job is to fit and test with a standard thermostat, I also have a 80c thermostat to try.

I feel like I have nearly solved it.

 

[clarkmichigan55b]

Glad you are making progress on your problem. With reference to my post No 63 if after fitting the correct thermostat it goes up to the 3/4 mark on the gauge when climbing this is quite normal. Just out of interest have you checked the function of the temperature sender unit?.

 

[Brightonrider]

I’ve sorted it!!!

This weekend I wanted to install my 80c thermostat (standard is 85c). I also wanted to address my loose fan belt and do a full citric acid flush. It has been a total success and I finally have a van that does not overheat on any hill. The citric flush pulled out a load of crap and I could see calcium deposits also in the flushed water. I had done multiple flushes previously but nothing touched it like the CA did.

What I did overall to the cooling system:
- Full fan belt revamp - pulleys, tensioners etc
- citric acid flush of the coolant system - really helped I feel
- long reach rad cap ( the standard Merc one wouldn’t build enough pressure)
- 80c thermostat
- new viscous clutch fan
- new Nissans rad
- new Merc water pump

All these things together sorted my cooling system but the final big push to really control the temps was the citric acid flush, the fan belt and 80c thermostat.

Now I have sorted this I will be gently increasing my turbo boost levels to aim for approx 150bhp as we are towing a 1900kg boat to France next year.

 

[star]

Glad it’s sorted, just be mindful that the ambient temp is lower, so the system is more efficient.

 

[clarkmichigan55b]

I second that also stars observation on ambient temperature.

 

[ajlsl600]

First thing - where is the intercooler placed? The intercooler is a source of heat. If it's in front of the radiator it reduces the ability of the radiator to transfer heat from the engine. Bearing in mind you're now burning more fuel which in turn makes more heat and you're getting a double whammy. I had a similar issue on my Defender when I fitted a hybrid turbo, cranked up the pump and fitted a full width intercooler mounted in front of the main radiator. Going back to the standard side mounted intercooler sorted the overheating. The eventual fix was simply a higher efficiency larger intercooler mounted next to a thicker radiator with more cooling cores. A larger radiator may be beneficial in your case too.

As for why your viscous fan doesn't work that's another question. Is it mounted behind the electric fan? If the electric fan isn't mounted right up against the radiator it may not be drawing hot air through the radiator.

One other thing - is the electric fan blowing the right way? Silly question but it wouldn't be the first time.

pretty much my own thoughts also maker designs frontal area air flow for that std installation and any other motor spec in that vehicle , can enough air get in?

 

[Brightonrider]

I have tested the engine in every season - this has been going on for 18months. It is not seasonal, it is fixed. Thanks for all the advice.

 

[umblecumbuz]

This thread is now several months old and I have just tracked it down, having learned a lot.

My interest is that I am about to buy an excellent 412D motorhome, 24 years old, and in the same ownership for most of that time.
I know nothing about the 412D, and am on a concentrated learning curve, so here's my first very basic question:
Is the 412D turbo'd from the factory, unlike the 420D?
... and where can I get info/workshop manual/any gleanings of facts, figures and tips for maintaining this beautiful machine?
Any pointers at all will be heartily welcomed.

 

[clarkmichigan55b]

Good afternoon,

The mechanical side should be ok but like anything it depends how it has been driven and cared for.
Has it had engine oil and filters and gear box / rear axle oil changes. Often overlooked brake fluid and antifreeze changes.
Turbo factory fitted.
Can have electric issues.
Is it a converted van or a chassis and cab?. Look out for rust.
Some MOT stations have failed the bottom ball joints for excessive play, this is normal on this type of vehicle.
Haynes do a manual for this vehicle.
One of the signs of a caring owner is the tyres, has it been fitted with premium brands or cheap and cheer full, and has the side walls been constantly been rubbed against the kerbs.
Check out the MOT history the link enclosed.
Hope this is of help.

Check the MOT history of a vehicle

Check the MOT history of a vehicle from 2005 onwards, including if it passed or failed, its mileage and why it failed, download MOT test certificate

www.gov.uk

 

[umblecumbuz]

Thank you clarkmichigan55b
The two gems that I've gleaned from your response are that Mr Haynes does a manual, which I'll obviously get - even though his standard has gone right down in recent times, plus your comment 'Can have electrical issues.'
It has had several advisories over the years for lighting and indicator gremlins, which are not too difficult to remedy, but also a tendency in recent times to drop into limp mode - cured by re-starting - at least that is what's happening according to the owners description. It's not OBDII compliant of course and has very few electronics, so this could be a future headache.

 

[Kev555]

If you can find somebody with Delphi diagnostic software and a 14 pin plug you should be able to narrow down the limp mode fault umblecumbuz? I remember hearing that it works with pre OBD Mercedes that have the round socket

 

[umblecumbuz]

If you can find somebody with Delphi diagnostic software and a 14 pin plug you should be able to narrow down the limp mode fault umblecumbuz? I remember hearing that it works with pre OBD Mercedes that have the round socket

So it looks like using an adaptor with my iCarsoft gear won't work?
(first, find an adaptor).
I was brought up on coils, plugs, condensers and points - then the early diesel period passed me by and I joined diesel when OBDII had already been established. So there is a huge knowledge gap with earlier diesels.
Gonna be fun!

 

[Brightonrider]

Just a follow up since my last one. Everything is running perfectly.
Been out this week and couldn't get the temp guage to get near the half way mark, let alone past it. I have added a rear cooling mod which diverts addition cool water to the rear cylinder as these tend to boil in extreme circumstances. I have also built a 2.5" stainless exhaust to keep the EGT's lower whilst boosting.