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Topic: 6v92 won’t start (Read 1631 times) previous topic - next topic

6v92 won’t start

Well, here's the newbie with another question. My '93 u300 6v92t just doesn't want to start when the engine is cold. I'm not talking cold weather. It's almost 60 degrees here. The first start is impossible without starting fluid. Once it starts for the first time it will start fairly easy after that. I've just replaced the start batteries. Checked and cleaned all the battery connections etc. even with the boost engaged the first start is not happening. I don't know the maintenance history on this coach. But I'm assuming it sat a lot. The breather coming off the pass side valve cover is dripping a small amount of oil. The last DD I worked on was in 1978. Kinda lost here.

Re: 6v92 won’t start

Reply #1 –
sounds like air in the fuel system...old seals or hose connections allow air in when it sits.

Re: 6v92 won’t start

Reply #2 –
You don't have a block heater, you have an almost useless thermostat housing heater. It does almost nothing for the block (because it's not installed in the block) but was an easy installation not really intended for cold weather. It heats the thermostat housing and the crossover pipe. In real world conditions, I turned on the "block heater" in Bishop, CA in the middle of winter. In the morning, I used my IR gun and found the block was stone cold but the thermostat housing and the crossover pipe were hot enough to burn my hand.

First, check to see that your heating element is getting juice. The switch is low next to the floor on the front of the bed. It glows when in the on position but that's not a real indication that the element is working and not burned out. Check after an hour for the temp of the thermostat housing and the crossover pipe. Be careful as it may be hot as I said above.

This is the block heater used on most Detroit 2 cycles from way back in the 1960's in the 71 series to now. Engine Heater kit fits Detroit Diesel 6V-92 WITH A/C compressor next to ...... It's 1500 watts, is the correct one for under the AC compressor. You will need a 20 amp outlet in a steel box to avoid overheating and melting (or worse) as this is a 1500 watt element.

This is the element used in Wanderlodges, buses, fire trucks, etc. The only drawback is the coolant will drain out when you install or remove it. The thermostat housing model will install without losing any.

The best solution is to install a remote block heater that supplies the block with heated coolant from hoses. Several members have done that. Several options to do that from electrical, propane or diesel fired block heaters.

You don't have a heated intake like a Cummins. Your Turbo 6V-92TA has a 17-1 compression ratio compared to the non-turbo 19-1. This makes a huge difference in cold weather starting.

Never use ether on a warm or hot engine. That can bend rods or break piston rings. Keep your three batteries in good shape with clean terminals. I installed an extra ground on ours. Also went to three 31 series batteries. No faster cranking but more CCA.

Turn off the in block installed heater before you crank the engine. An air bubble can overheat the element and cause it to fail.

Pierce

Re: 6v92 won’t start

Reply #3 –
John, Pierce is THE guru for Detroits.

Before we had the inframe overhaul, five years ago, I had to have the "block" heater on overnight if I expected to start the engine when air temp was under 60. After the overhaul the engine will start without the block heater in the 50's.

Open the rear hatch and your "block" heater is on the left Turn it on, dig out your IR gun, and head out to the back of the coach. If your heater is working you will be able to see a temperature increase in that tank within a couple of minutes. You may also be able to hear it working.

This year's service plan includes changing the coolant, so I'm going to try to remember to have the block heater installed where it ought to be at the same time.

Re: 6v92 won’t start

Reply #4 –
When your Detroit does finally start in cold weather, it fires on one, then two then perhaps 4 or 5 before settling down with all six firing. Clouds of white smoke kill all the bugs and tent campers in the area. Much worse at higher altitudes.

Pierce

Re: 6v92 won’t start

Reply #5 –
Quote from: kb0zke –
John, Pierce is THE guru for Detroits.

Before we had the inframe overhaul, five years ago, I had to have the "block" heater on overnight if I expected to start the engine when air temp was under 60. After the overhaul the engine will start without the block heater in the 50's.

Open the rear hatch and your "block" heater is on the left Turn it on, dig out your IR gun, and head out to the back of the coach. If your heater is working you will be able to see a temperature increase in that tank within a couple of minutes. You may also be able to hear it working.

This year's service plan includes changing the coolant, so I'm going to try to remember to have the block heater installed where it ought to be at the same time.
David,

Unless the mechanic who did the overhaul was really knowledgeable, you may have have 19 to 1 pistons now. They look about the same. This is a common mistake (or not) Several different compression ratios are available. My Buffalo Bus with the 8-71 Detroit started instantly in cold weather. My fire trucks started so fast that it was impossible to push the start button and get your finger off without starting the engine and never a trace of smoke. This is what 19-1 does for you. Probably not a big deal in an RV for reducing the TBO (time between overhaul).

I think Ken Hathaway uses a block heater to bring it up to temp each time in cold weather so it's an instant start without smoke.

I should have added that all 92 series Detoits are not the same. They started mechanical and later electronic. Some like ours are aftercooled with the cooler below the blower, some are intercooled like Cummins. For stationary generator engines, the choice of pistons (compression ratio) depended on the altitude. When Roger Penske bought Detroit Diesel, the electronic engines and blower bypass was supposed to be good for 22% better fuel mileage. Since Mercedes bought Detroit, they still make new 6V-92TAs for military and overseas sales while supplying domestic parts, blocks, etc.

If you are a new owner and have not checked, look at your hydraulic belt for the fan motors/pump. It will probably be out of alignment and it a potential fatal mistake. The steering wheel is in the way of the warning lights and if the belt comes off and the engine overheats, you won't see the light. The DDEC will go to half power for 30 seconds and then shut down. If you use the override button, you can damage the engine. Once, perhaps to move the coach to a safe location and that's all. Real the old posts on how to align the pulleys. It's easy.

Pierce

Re: 6v92 won’t start

Reply #6 –
Thanks, Pierce. I checked and my rig is set up with both of those block heaters, but neither of them  work. Just ordered the one you gave as an example. Since I'll be draining the cooling system to replace the heater. What coolant should I use after I drain and flush the system?

Re: 6v92 won’t start

Reply #7 –
Quote from: John Yager –
Thanks, Pierce. I checked and my rig is set up with both of those block heaters, but neither of them  work. Just ordered the one you gave as an example. Since I'll be draining the cooling system to replace the heater. What coolant should I use after I drain and flush the system?
I had the same question a few years back and looked at the recommended choices from Detroit. Then I went down to the West Sacramento Detroit dealer and asked the shop foreman. He said, "anything that's green." Go to Detroit Diesel's publication here on page 5: https://www.wanderlodgeownersgroup.com/downloads/Detroit%20Diesel%20Coolants.pdf  This is good to save as a PDF for quick reference.

Since a big percentage of Wanderlodges, Bluebirds have Detroits in them, they are an excellent group to join. I met a bunch of them in Death Valley on the way back from Q in '14 or '16. Really nice club. I talked to one owner who needed to replace his block heater but the bottom of the block location meant that he had to wait until he could drain the coolant to do the job. A big plus for a remote block heater. No spillage and you don't have to worry about a air bubble.

Pierce

Re: 6v92 won’t start

Reply #8 –
Assuming you know or have discovered the type of oil to use, the hand diesel primer, etc, etc. Lots of little tricks to a trouble free ownership. If not, call or message me.

Pierce

Re: 6v92 won’t start

Reply #9 –
Delo D100 40wt.is what I'll be using. This rig has been a few miles. 207000 to be exact. The previous owners have taken decent care of it. But  I like trouble free traveling. So, if I'm not sure about something I'll just go through that system until I know it's right. I'm sure I'll be leaning on all of the knowledge in this forum. You guys haven't failed to come through on every question I've had so far. Thanks.

Re: 6v92 won’t start

Reply #10 –
I do indeed use the engine heater whenever I have 120v. Makes startup a non-issue.

Here is the heater I installed low on the block behind the dash air compressor.

Hot start Block Heater # DDV-151B 1500 Watts

I wired the new block heater on a separate circuit. When above 50º I just use the lower heater. Below 50º I use both.

see ya
ken

Re: 6v92 won’t start

Reply #11 –
Ken has it done the way it should have been originally and the way most all Detroits have it located. Just make sure the block heater has the spacer so the cord can come out and not be squashed by the compressor mount when it's tightened down. You are going to have to drain the coolant to install it.

The other way and perhaps the best is to do a remote block heater with short hoses to the engine. With shut offs, you can change the heater or do maintenance on it without losing any coolant. Hotstart has been around for a long time. Hotstart TPS151GT10-000 Engine Block Heater Bottle Type 1500w 120V - Brand...

Pierce
 

Re: 6v92 won’t start

Reply #12 –
In case you have not read the past posts about starting the 6V-92TA engines, basically, they don't have much of a way to heat the block in our coaches as them come from the Foretravel plant. Since they are turbocharged, the pistons are 17 to 1 compression ratio compared to the 19 to 1 compression ratio in the naturally aspirated 6V-92. Two points less in compression ratio makes starting very much harder in cold weather unless the block is heated. Some owners install the higher compression pistons to achieve better cold weather starting. The liners are also different so the intake port height should be checked to make sure the induction timing will not be effected. Our 6V-92TA engines are aftercooled, not intercooled and may even have two piece pistons with a even lower 15 to 1 compression ratio. This engine will be very difficult to start in cold weather without aux block heating.

Pierce